A handbook of plant tissue culture, by Philip R. White...

Work of Gautheret, Nobecourt, and White led to the first really successful prolonged cultivation of undifferentiated plant tissues.

“With the work of his com- patriot Nobecourt (Nobecourt, 1937, 74, 1938, 75, 76, 1939, 77; Nobecourt and Dusseau, 1938, 311), and with White's (Fig. 12) independent work in America, these studies have led to the first really successful prolonged cultivation of undifferenti- ated plant tissues (White, 1939, 78, 333) .”

• cites Nobecourt, 1937Not matched

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• cites Nobecourt, 1938 sourceSupported
• cites White, 1939 sourceNot checked — no full text of the source

Animal tissue cultures and cultures of undifferentiated plant materials generally behave alike under a given set of conditions.

“This is generally true of animal tissue cultures (Ebeling, 1921, 456; Parker, 1932, 422, 423, 1938, 26) and cultures of undifferentiated plant materials (White, 1939, 78).”

• cites Ebeling, 1921, 456 sourceSupported
• cites Parker, 1932, 422, 423Not matched

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• cites White, 1939, 78 sourceNot checked — no full text of the source

Lund and Rosene and Lund have shown that there is a corresponding electropotential gradient which can be modified by imposing artificial oxygen-hydrogen gradients.

“Lund (1931, 247) and Rosene and Lund (1935, 319) have shown that there is a correspond- ing electropotential gradient which can be modi- fied by imposing artificial oxygen-hydrogen gradi- ents.”

• cites Lund (1931, 247) sourceNot checked — no full text of the source
• cites Rosene and Lund (1935, 319) sourceSupported

Kotte in 1922 made the first important experimental contribution to plant tissue culture by working with colorless meristems, excised root tips.

“In 1922 one of his students, Kotte, 51, 52, (Fig. 10) made the first important experimental contribution to the sub- ject.Kotte chose to work not with single, green, mature cells, but with colorless meristems, excised root tips.”

• cites Kotte, 51, 52Not matched

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Attempts to duplicate Carrel's and Lewis' results with plant tissues by use of a natural nutrient comparable to embryo juice have consistently failed, with one possible exception.

“Attempts were, of course, made to duplicate Carrel's and Lewis' brilliant results, with plant tissues, by use of some”

• cites Schmucker, 1929, 110Not matched

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In the hands of other workers, all preparations of tissue juices, xylem sap, phloem exudate, liquid endosperm, etc., have given evidence of toxicity.

“In the hands of other workers, all preparations of tissue juices, xylem sap, phloem exudate, liquid endosperm, etc., have given evidence of toxicity”

• cites Prat, 1927, 451Not matched

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• cites Bobbins, 1922, 177Not matched

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• cites Bobbins and V. B. White, 1937, 178Not matched

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The most satisfactory results with Kotte's root tips, maintaining normal development and response for considerable periods, were obtained in a solution containing the salts, 1 per cent dextrose plus 5 g Liebig's meat extract per liter.

“The most satisfactory results, in which normal development and response were maintained for considerable periods, were ob- tained in a solution containing, besides the salts, 1 per cent dextrose plus 5 g.Liebig's meat extract per liter.”

• cites Kotte, 51, 52Not matched

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Vochting's grafting and transplantation experiments confirmed that no matter the environment or host, a scion always developed in a pattern fixed by the species from which it came.

“Vochting's second approach involved the age-old method of grafting (Fig. 2) or transplantation (1892, 330, 1894, 331) and merely confirmed what had been known from time immemorial, that no matter what the environ- ment or host into which a scion was transplanted, it always developed in a given pattern which was fixed by the species from which it came.”

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• cites [330]Not matched

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• cites [1894]Not matched

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• cites [331]Not matched

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Attempts at synthesis of a nutrient led by Dr. and Mrs. Warren H. Lewis and Dr. A. H. Drew have not been much more successful in eliminating the unknowns.

“Nor have the attempts at a synthesis of a nutrient, led by Dr. and Mrs. Warren H. Lewis (Figs. 7 , 8) in this country and Dr. A. H. Drew in England been much more successful in eliminating the unknowns”

• cites Baker, 1936, 234Not matched

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• cites Drew, 1922, 145Not matched

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• cites M. R. and W. H. Lewis, 1911, 149-151Not matched

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Vochting's transplantation experiments showed that physiological behavior was also fixed by species and could not be altered by contact with or dependence on tissues of another species.

“Not only was the developmental pattern fixed, but the physiological behavior was also fixed by the spe- cies and could not be altered by contact with or even dependence on the tissues of another species (Vochting, 1894, 331).”

• cites Vochting, 1894, 331Not matched

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There is some evidence that long-period cultures may be built up by a recurrent cyclic reutilization of materials leached out of older inactive or even dead tissues.

“There is some evidence that such cul- tures may be built up by a recurrent cyclic re- utilization of materials leached out of the older inactive or even dead tissues.”

Flask cultures require large volumes of nutrient.

“and they require large volumes of nutrient.”

Contrary to expectation, morphological changes that might be anticipated in long culture periods have not actually appeared.

“Contrary to expectation, morphologi- cal changes which might be anticipated have not actually appeared.”

Flask and tube methods do not permit the observer to follow the behavior of individual cells except under conditions entailing more or less serious disruption of the continuity of growth.

“But these methods do not permit the observer to follow the behavior of individual cells except under condi- tions which entail a more or less serious disruption of the continuity of growth.”

With tomato, branch dominance usually develops after the branch has reached a length of about 20 mm.

“With tomato this dominance usually develops after the branch has reached a length of about 20 mm.”

A solution of calcium hypochlorite containing 1 per cent chlorine gives fairly satisfactory seed sterilization if seeds are shaken in it for 15 to 30 minutes, then washed in sterile distilled water.

“A solution of calcium hypochlorite containing 1 per cent chlorine will give fairly satisfactory re- sults (Wilson, 1915, 455;White, 1932, 63) if seeds are shaken therein for 15 to 30 minutes, then washed in sterile distilled water and placed in Petri dishes.”

• cites Wilson, 1915, 455 sourceNot checked — no full text of the source
• cites White, 1932, 63 sourceNot checked — no full text of the source

The tissue culture technique permits building up vegetatively derived clones, all members derived by division of a single ancestral fragment so that all members have exactly the same genetic constitution.

“The tissue culture technique has in this respect one great advantage over most other cul- ture practices-that it permits the building up of vegetatively derived clones, all members derived by division of a single ancestral fragment so that all members have exactly the same genetic consti- tution.”

Cambium offers, of all major meristematic regions except the medullary rays, perhaps the most difficulties in isolating fragments aseptically without too great injury.

“Practically, however, it offers of all the major meristematic regions except the medullary rays perhaps most difficulties in the way of isolating fragments aseptically without too great injury (White, 1931, 32).”

• cites White, 1931, 32Not matched

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Neither flask nor tube method permits microscopic examination of cultures.

“Neither method permits microscopic examination of cultures.”

Some adventitious roots from infected cuttings regularly remain sterile and can serve as origins for clones of sterile root cultures carrying the virus of the original infection.

“Some, however, will regu- larly remain sterile.These can then be made to serve as the origins for clones of sterile root cul- tures each carrying the virus of the disease with which the original cutting was infected.”

If a piece of old tissue carrying several branch initials but from which the apex has been removed is cultured for a time, a considerable proportion of these initials will establish themselves with a comparable degree of dominance.

“Experience has shown that, if a piece of old tissue carrying several branch initials but from which the apex has been removed is cul- tured for a time, a considerable proportion of these initials will establish themselves with a comparable degree of dominance.”

All cultures except those maintained at 35° and 40° show an immediate reversion to the growth rate typical for 22° after transfer to 22°C.

“All except those maintained at 35° and 40° show an immediate reversion to the growth rate typical for 22°.”

• cites White, 1937, 266 sourceNot checked — no full text of the source

Cultures endure low temperatures down to +5°C for long periods.

“Cultures will, on the other hand, endure low temperatures-down to + 5° C.-for long periods”

A two-month culture period requires only an eighth as much work as eight one-week periods.

“A two-month period thus requires only an eighth as much work as do eight one-week periods.”

Bromine gas gives the most satisfactory surface sterilization of seeds.

“The most satisfactory result is to be obtained with bromine gas (Klein u.Kisser, 1924, 299; Burlet, 1936, 207).”

• cites Klein u.Kisser, 1924, 299Not matched

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• cites Burlet, 1936, 207Not matched

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Measurement of the central axis alone, ignoring all branches, is in error by about 5 to 8 per cent as compared to dry weights.

“Measurement of the central axis alone, ignoring all branches, is in error by about 5 to 8 per cent as compared to dry weights.”

The first three methods of measuring plant tissue cultures require destruction of the tissue studied.

“The first three methods require the destruction of the tissue studied.”

Root and callus cultures show a considerable degree of variability.

“root and callus cultures, since they are biological mate- rials, show a considerable degree of variability.”

In experiments in which roots were fixed in a constantly aerated medium lacking an oxygen gradient, the geotropic response reappeared.

“Yet in experiments in which roots were fixed in a constantly aerated medium lacking an oxygen gradient, the response reap- peared (White, unpublished).”

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Roots floated on or near the surface of a liquid substratum show no geotropic response in this laboratory's experience.

“It has been the experience of this laboratory that roots floated on or near the surface of a liquid sub- stratum show no such response.”

This variability is fairly typical of root cultures.

“This is fairly typical of root cultures.”

One series of 20 cultures studied in June 1939 in the control nutrient had a total linear increment of the main axes of 7449 mm in a week's time.

“one series of 20 cultures studied in June, 1939, in the control nutrient, had a total linear increment of the main axes of 7449 mm. in a week's time.”

By this method, measurements can be made with surprising accuracy.

“By this method, measurements can be made with sur- prising accuracy.”

In Nicotiana callus tissue, stem growing points and leaves of a high order of differentiation developed under submerged, reduced-aeration conditions from a tissue mass that appeared to have lost the capacity to differentiate on semi-solid nutrient.

“Here the culture was submerged and thus subject to reduced aeration, stem grow ing points and Leaves of n high order of differentiation have, under the latter conditions, developed from n tissue mass which, on the semisolid nutrient, appeared to have lost the capacity to differ- entiate.”

• cites White, P. R. L939.Not matched

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A unidirectional flow of liquid through immersed root organs was demonstrated.

“means were devised which made possible the demonstration of the existence of a unidirectional flow of liquid through these immersed organs (White, 1936, 264).”

• cites White, 1936, 264Not matched

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Differences up to 12 per cent between two series are without statistical significance.

“differences up to 12 per cent between the two series (Nos. 1, 2, 3, 4, and 10) are without statistical significance”

Differences of 24 and 25 per cent are of doubtful significance, with odds of less than 20:1 against the results being due to chance.

“differences of 24 and 25 per cent (Nos.5 and 8) are of doubtful significance (odds of less than 20 : 1 against the results being due to chance)”

Amino-nitrogen measurement requires the destruction of the material measured.

“This is the fact that it requires the destruction of the material measured.”

Root cultures immersed in nutrient fluid form well differentiated vascular strands.

“Root cultures, although immersed in nutrient fluid, nevertheless form well differentiated vascular strands (Fig. 55).”

A culture of Nicotiana callus maintained for 8 weeks in an undifferentiated state by repeated transfer on a semi-solid nutrient and then placed for 2 weeks in a liquid nutrient showed reduction in available oxygen supply resulting in formation of differentiated growing points and leaves.

“A culture of Nicotiana callus maintained for 8 weeks in an undifferentiated state by repeated transfer on a serni-solid nutrient and then placed for 2 weeks in a liquid nutrient.Reduc- tion in available oxygen supply under the latter conditions has resulted in the formation of differentiated growing points and leaves, x 7.5.”

• cites White, P. R. 1939. Bull. Torrey Bot. Club 66: 509, fig.2, 333.Not matched

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Recent work in plant tissue culture has been concentrated on the meristems.

“Kecent work in this field has, therefore, been concentrated on the meri- stems.”

When established in culture, cambium behaves much as do cultures derived from procambium.

“When established in culture, it behaves much as do cul- tures derived from procambium.”

Efforts to establish similar cultures of plant tissues were fruitless until 1922 when Kotte and Robbins independently cultivated excised root tips for brief periods.

“Efforts aimed at the establishment of similar cultures of plant tissues were fruitless until 1922 when Kotte and Rob-bins independently cultivated excised root tips for brief periods.”

• cites Kotte, 1922Not matched

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• cites Robbins, 1922Not matched

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Intercalary meristems require considerable manipulation for excision and therefore suffer rather severe injury.

“The intercalary meristems require considerable manipulation for their excision and therefore suf- fer rather severe injury.”

The only intercalary meristem successfully grown is that from the procambial region of tobacco.

“The only intercalary meristem which has been successfully grown is that from the pro- cambial region of tobacco (White, 1939, 78).”

• cites White, 1939 sourceNot checked — no full text of the source

Cotyledons will usually regenerate easily.

“Cotyledons will usually re- generate easily (Molliard, 1921, 106;Behre, 1929, 275).”

• cites Molliard, 1921Not matched

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• cites Behre, 1929Not matched

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Tukey's results with older embryos of stone-fruits indicate considerable progress toward culturing egg cells.

“Indeed, Tukey 's results with older embryos of stone-fruits indicate considerable progress.”

• cites Tukey, 1933 sourceNot checked — no full text of the source

Excised root tips maintain for the most part their normal morphology, branching and extending in a regular way.

“They main- tain for the most part their normal morphology, branching and extending in a regular way.”

Available evidence indicates that when a meristematic function is resumed by cells at any point in the plant body, as in healing internal wounds, these cells are for the most part not truly mature.

“But available evidence seems to indicate that, when a meristematic function is resumed by cells at any point in the plant body, as in the case of healing internal wounds, these cells are for the most part not truly mature (Schilling, 1915, 321, 1923, 322 ; Jaeger, 1928, 298) .”

• cites Schilling, 1915Not matched

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• cites Schilling, 1923Not matched

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• cites Jaeger, 1928Not matched

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Excised stem tips have been grown with some success by Robbins, White, Avery and LaRue, Behre, and others.

“Hence, although excised stem tips have been grown with some success by Robbins (1922, 57), White (1933, 116), Avery and LaRue (1938, 237), Behre (1929, 275), and others, such cultures have not proved of great value to the tissue culture field and have not been pushed very far.”

• cites Robbins, 1922Not matched

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• cites White, 1933Not matched

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• cites Avery and LaRue, 1938Not matched

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It is possible to cut an embryo into bits and grow any one of these fragments.

“It is, therefore, possible to cut an embryo into bits and grow any one of these fragments.”

Details of root morphology are characteristic for different species.

“The details of this morphology are characteristic for different species (Figs. 13, 21-24).”

The whole gene mechanism, as exemplified in somatic cells, seems to lose its meaning without the concept of cell totipotency.

“The whole gene mechanism, as exemplified in somatic cells, seems to lose its meaning without this concept.”

Epidermal tissue retains meristematic capacity ordinarily for somewhat shorter periods than those tissues.

“Epidermal tissue does so ordi- narily for somewhat shorter periods (Naylor, 1931, 308 ; Naylor and Johnson, 1937, 309 ; Naylor and Sperry, 1938, 310)”

• cites Naylor, 1931Not matched

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• cites Naylor and Johnson, 1937 sourceNot checked — no full text of the source
• cites Naylor and Sperry, 1938Not matched

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All tissues that have given promise of being grown satisfactorily, with the single exception of Schmucker's uncorroborated report on leaf-mesophyll cells, have been meristematic tissues.

“If plant tissues are classified according to their ob- served usefulness as culture material, it becomes immediately obvious that all of the tissues which have given promise of being grown satisfactorily, with the single exception of Schmucker's uncor- roborated report (1929, 110) on leaf-mesophyll cells, have been meristematic tissues.”

• cites Schmucker, 1929Not matched

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The regeneration of leaves and roots from tissues which are neither leaf nor root points to the existence of capacities called forth only by exceptional circumstances.

“The regen- eration of leaves and roots from tissues which are neither leaf nor root points to the existence of capacities which are called forth only by exceptional circumstances.”

Cases exist where viable embryos are initiated but endosperm is not developed so that the embryos die of starvation.

“Noteworthy among these are the fairly numerous cases where viable embryos are initiated but where, for one reason or another, endosperm is not developed so that the embryos die of starvation.”

The toxicity of natural plant preparations forced workers in plant tissue culture to develop an essentially synthetic medium step by step.

“This has, of course, forced workers in the plant tissue culture field to resort to the much more tedious, difficult, and uncertain, but at the same time when successful more satisfying method of developing step by step an essentially synthetic medium.”

There is a very marked and wide difference in degree of apical dominance among roots.

“There is, for example, a very marked and wide difference in degree of apical dominance (White, 1938, 66).”

• cites White, 1938Not matched

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Trichomes, guard cells, xylem fibers, etc., retain meristematic capacity for only very brief periods.

“while such cells as tri- chomes, guard cells, xylem fibers, etc., retain this capacity for only very brief periods (Haberlandt, 1913, 294, 1914, 295, 1919, 245, 296, 1920, 297, 1921, 354), because of mechanical modifications if for no other reason.”

• cites Haberlandt, 1913Not matched

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• cites Haberlandt, 1914Not matched

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• cites Haberlandt, 1919Not matched

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Hypocotyl is in general still more refractory than other embryo regions.

“Hypocotyl is in general still more refractory”

Cultivation of such embryos, as practiced, results in entire plants which differ in no wise from plants obtained from viable seed by more usual methods.

“However, since the culti- vation of such embryos, as practiced, results in entire plants which differ in no wise from plants obtained from viable seed by the more usual meth- ods, such cultures are likely to prove of value only in special cases.”

Even in the embryo there are some regions having a greater proliferative capacity than others.

“But, as Smith (1907, 325), Molliard (1921, 106), LaRue (1936, 82, 104), Dau- phine (1929, 94), and others have shown, even in the embryo there are some regions having a greater proliferative capacity than others, an observation which agrees with that established in animal embryology.”

• cites Smith, 1907Not matched

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• cites Molliard, 1921Not matched

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• cites LaRue, 1936Not matched

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Gas is extremely toxic to plant materials.

“Gas is extremely toxic to plant materials and unburned gas may easily be occluded in the culture flasks if the mouths are flamed (Saeger, 1933, 261).”

• cites Saeger, 1933, 261Not matched

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Egg cells and embryos, insofar as they have been grown in culture, have given rise to complete plants.

“Eggcells and embryos, insofar as they have been grown in culture, have given rise to complete plants.”

Tissues that fail to grow without thiamin are clearly unable to synthesize thiamin.

“Here the tissues are clearly unable to synthesize thiamin.”

Cotton itself contains significant quantities of thiamin.

“Cotton itself contains significant quantities of thiamin (Schopfer et Rytz, 1937, 226).”

• cites Schopfer et Rytz, 1937, 226Not matched

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The problem of growing excised roots should be relatively simple from both a mechanical and a physiological point of view.

“The problem of growing excised roots should, therefore, both from a mechanical and a physiological point of view, be rela- tively simple.”

Water makes up approximately 97 per cent of the mass of all nutrients.

“Since water makes up approximately 97 per cent of the mass of all nutrients, while some other ingredients are required in amounts repre- sented by ten-thousandths of a per cent, the purity of the water used is of prime importance and can- not be overemphasized (White, 1932, 63, 1933, 141).”

• cites White, 1932, 63, 1933, 141 sourceNot checked — no full text of the source

Organic materials from the phloem must travel considerable distances by diffusion through other cells before reaching the dividing cells.

“a glance at the anatomy of a rapidly growing root shows that these materials, coming from the phloem, must travel for considerable distances by diffusion through other cells before they can reach the dividing cells themselves.”

Plant tissue cultures have an optimum temperature only slightly above room temperature, about 27°-30° C.

“Since plant tissue cultures are extremely sensitive to temperature fluctuations (White, 1932, 63, 1937, 265, 266) and have an optimum temperature only slightly above room temperature (about 27°-30° C), it is impor- tant that even the room used for routine stock cultures be air-conditioned, with faciilties for cooling in extremely hot weather.”

• cites White, 1932, 63, 1937, 265, 266 sourceNot checked — no full text of the source

There is to date no evidence that any sugar other than sucrose needs to be employed.

“There is to date no evi- dence that any sugar other than sucrose needs to be employed.”

Aside from maintained temperature level and protection from direct insolation and traces of gases or volatile materials, the environmental requirements of plant tissue cultures are not especially exacting.

“Aside from these two requirements, of maintained tem- perature level and protection from direct insola- tion, together with protection from traces of gases or volatile materials, the environmental require- ments of plant tissue cultures are not especially exacting.”

Glucose and fructose have been employed in some media, particularly those used for the cultivation of tissues of monocotyledonous plants, but with results which have not been entirely satisfactory.

“Glucose and fructose have been em- ployed in some media, particularly those used for the cultivation of tissues of monocotyledonous plants, but with results which have not been en- tirely satisfactory (Kotte, 1922, 51, 52; Robbins, 1922, 57 ; Robbins and Maneval, 1923, 59 ; Robbins and V. B. White, 1937, 178; Malyschev, 1933, 53, 54; White, 1932, 63, 1940, 172, 173).”

• cites Kotte, 1922, 51, 52Not matched

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• cites Robbins, 1922, 57Not matched

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• cites White, 1932, 63, 1940, 172, 173 sourceNot checked — no full text of the source

The only universally necessary member of the vitamin group seems to be thiamin (vitamin B1).

“The only universally necessary member of this group seems to be thiamin (vitamin B x ) (Bonner, 1937, 198, 199; Robbins and Bartley, 1937, 222, 223 ; White, 1937, 231 ; Gautheret, 1938, 69 ; Nobecourt, 1938, 75).”

• cites Bonner, 1937, 198, 199 sourceNot checked — no full text of the source
• cites Robbins and Bartley, 1937, 222, 223Not matched

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• cites White, 1937, 231 sourceNot checked — no full text of the source

Kotte's and Robbins' early work supported the supposition that growing excised roots is relatively simple.

“Kotte's (1922, 51, 52) and Robbins' (1922, 57) early work supported this supposition.”

• cites Kotte, 1922Not matched

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• cites Robbins, 1922Not matched

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Plant tissue cultures are extremely sensitive to temperature fluctuations.

“Since plant tissue cultures are extremely sensitive to temperature fluctuations (White, 1932, 63, 1937, 265, 266) and have an optimum temperature only slightly above room temperature (about 27°-30° C), it is impor- tant that even the room used for routine stock cultures be air-conditioned, with faciilties for cooling in extremely hot weather.”

• cites White, 1932, 63, 1937, 265, 266 sourceNot checked — no full text of the source

Increment figures obtained at the end of a long culture period may give no true measure of the level of metabolic activity of the tissue involved.

“The increment figures obtained at the end of a long period may thus give no true measure of the level of meta- bolic activity of the tissue involved.”

Much of the variability in root cultures probably arises from differences in age, state of nutrition, degree of established dominance, extent of excision trauma, and similar characteristics of separate explants.

“Much of the variability, however, probably arises from differences in age, state of nutrition, degree of established dominance, extent of ex- cision trauma, and similar characteristics of the separate explants.”

In many types of tissues, the requirement for thiamin becomes evident in complete failure of the cultures if thiamin or thiazole is not included in the nutrient.

“In many types of tissues, this requirement becomes evident in com- plete failure of the cultures if thiamin or thiazole is not included in the nutrient (Bonner, 1937(Bonner, , 198, 1938, 199; Robbins and Bartley, 1937, 222, 223; White, 1937, 231, 1939, 182 ; Bonner and Devirian, 1939, 205).”

• cites Bonner, 1937, 198 sourceNot checked — no full text of the source
• cites Robbins and Bartley, 1937, 222, 223Not matched

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• cites White, 1937, 231, 1939, 182 sourceNot checked — no full text of the source

Part of the variability in root cultures arises from slight and unrecognized differences in environmental conditions to which individual flasks are subjected.

“Part of this variability doubtless arises as a result of slight and unrecognized differences in the environmental conditions to which individual flasks are subjected.”

There is some evidence that galactose may be quite toxic.

“There is some evidence that galactose may be quite toxic (White, 1940, 173).”

• cites White, 1940, 173 sourceNot checked — no full text of the source

Hanging-drop cultures appear to be best for following the behavior of individual cells.

“For this purpose, hanging-drop cultures (see Parker, 1938, 26), in spite of numerous objection- able characteristics, appear to be best.”

• cites Parker, 1938, 26Not matched

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Examination of the history of plant tissue cultures shows that only those tissues have so far been successfully cultivated which possess a fundamentally meristematic character and do not have to undergo any major degree of de-differentiation.

“Examination of the history of plant tissue cul- tures shows that only those tissues have so far been successfully cultivated which possess a fun- damentally meristematic character and do not have to undergo any major degree of de-differen- tiation.”

Cultures maintained in an ordinary laboratory room without air-conditioning show a marked seasonal variation in growth rate.

“Cultures maintained in an ordinary laboratory room without such control show a marked seasonal variation in growth rate (Fig. 26) (White, 1937, 265) and may, in extreme weather, suffer serious injury.”

• cites White, 1937, 265 sourceNot checked — no full text of the source

Large masses of tissue accumulated in a long culture period may be largely inert carbohydrate-cell-wall materials, starch, etc.

“Moreover, the large masses of tissue accumulated in a long period may be largely inert carbohydrate-cell-wall materials, starch, etc.”

Sucrose is a completely satisfactory carbohydrate for all plant tissues which have so far been grown successfully.

“Fortunately, the much more easily purified and more stable disaccharide, su- crose, is a completely satisfactory carbohydrate for all plant tissues which have so far been grown suc- cessfully (White, 1934, et seq., 65, 66, 78, 172, 173; Fiedler, 1936, 45; Robbins and Bartley, 1937, 222; Robbins and Schmidt, 1938, 60; Thielman, 1938, 171).”

• cites White, 1934, et seq., 65, 66, 78, 172, 173 sourceNot checked — no full text of the source
• cites Fiedler, 1936, 45Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Robbins and Bartley, 1937, 222Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Thiamin or its precursors have been shown to be essential for, or at least highly beneficial to, the growth of a great variety of plant parts.

“Thiamin or its precursors have been shown to be essential for, or at least highly beneficial to, the growth of a great variety of plant parts.”

The natural root substratum is a fairly complex solution of salts, humic acids, and other simple organic compounds.

“This substratum is, in nature, a fairly complex solution of salts, humic acids, and other sim- ple organic compounds.”

These organic materials have proved to be relatively simple substances.

“It might, therefore, be anticipated that these organic materials would prove to be relatively simple substances, as indeed they have (see later).”

Unburned gas may easily be occluded in culture flasks if the mouths are flamed.

“Gas is extremely toxic to plant materials and unburned gas may easily be occluded in the culture flasks if the mouths are flamed (Saeger, 1933, 261).”

• cites Saeger, 1933, 261Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Until more is known about pith, cortex, epidermis, and other such tissues, they cannot be looked upon as satisfactory material for plant tissue cultures.

“but until a great deal more is known about them than at present they cannot be looked upon as satisfac- tory material for plant tissue cultures.”

Plant tissues require for satisfactory growth at least eleven elements besides oxygen, hydrogen, and carbon: calcium, potassium, magnesium, nitrogen, sulfur, phosphorus, iron, manganese, zinc, boron, and iodine.

“Plant tissues require for satisfactory growth at least eleven elements besides oxygen, hydrogen, and carbon.These are calcium, potas- sium, magnesium, nitrogen, sulfur, phosphorus, iron, manganese, zinc, boron, and iodine.”

• cites White, 1933, 141, 1937, 142, 143, 1938, 144Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Berthelot, 1934, 136Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Bobbins, V. B. White, et al., 1936, 139Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Plant tissue cells do not migrate along a solid substratum.

“Plant tissue cells do not migrate along a solid substratum (Chambers, 1923, 43 ;Pfeiffer, 1933, 450 ;Scheitterer, 1931, 109, andGautheret, 1937, 282, notwithstanding)”

• cites Chambers, 1923, 43Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Pfeiffer, 1933, 450Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Scheitterer, 1931, 109Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Nicotinic acid appears to be equally important for a somewhat smaller number of plants such as legumes.

“Nicotinic acid appears to be equally important for a somewhat smaller number of plants such as legumes (Bonner, 1938, 200; Addicott and Bonner, 1938, 197 ; Bonner and Axtman, 1937, 203 ; Bonner and Devirian, 1939, 205).”

• cites Bonner, 1938, 200Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Addicott and Bonner, 1938, 197Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Bonner and Axtman, 1937, 203Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Tissue and organ cultures furnish unusually clean, uniform, easily handled material for histological study.

“Tissue and organ cultures furnish unusually clean, uniform, easily handled material for histo- logical study.”

The capacity of tissue to adjust its behavior towards widely different substances appears about the same irrespective of the substance under investigation.

“The capacity of the tissue to adjust its behavior vis a vis these widely different substances appears to be about the same, irrespective of the substance under investigation.”

Changes in mass and form are only secondary symptoms of the real activity of the tissue and must be interpreted with caution.

“changes in mass and in form are only secondary symptoms of the real activity of the tissue and must be interpreted with some caution.”

Both callus cultures and root cultures should provide ideal material for study of fermentation/respiration because of reduced dimensions permitting easy gas interchange, freedom from trauma, and high growth rates.

“Both callus cultures and root cultures, because of their rela- tively reduced dimensions which permit a com- paratively easy gas interchange between culture and nutrient, because of their freedom from trauma, and because of their high growth rates, should provide ideal material for study of proc- esses of this sort”

• cites Warburg, 1923, 272, 1926, 273Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Roots in culture ordinarily take up a diameter characteristic of the species and of the culture medium within a very few millimeters of the growing point and retain this diameter throughout the length of even very old cultures.

“As a result, they ordinarily take up a diameter characteristic of the species and of the culture medium within a very few milli- meters of the growing point and retain this diam- eter throughout the length of even very old cul- tures”

When grown in culture, roots do not undergo secondary thickening.

“When grown in culture, roots do not undergo secondary thicken- ing (White, 1934, 65).”

• cites White, 1934, 65 sourceNot checked — no full text of the source

Viruses of a considerable number of diseases of the mosaic group have been cultivated in excised roots of tomato.

“Viruses of a consider- able number of diseases of the mosaic group have been cultivated in excised roots of tomato (White, 1934, 438, 1936, 439).”

• cites White, 1934, 438, 1936, 439 sourceNot checked — no full text of the source

With at least 20 replications in each environmental complex, a difference of at least 30 per cent of the control value must be produced by any given variable before that variable can safely be assumed responsible for the difference.

“In order to reduce the random error, each experiment should include at least 20 replications in each environmental complex, and with this number a difference of at least 30 per cent of the control value must be produced by any given variable before that variable can safely be assumed to be responsible for the difference.”

Fiedler verified that the weights and linear increments of root cultures bear a constant relation to one another by parallel measurements and weighings of a series of cultures of different length.

“Fiedler (1936, 45) has verfied the fact that the weights and linear increments of root cultures bear a constant relation to one another, by parallel measurements and weighings of a series of cultures of different length.”

• cites Fiedler (1936, 45)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

A correlative diurnal rhythm in respiration rate has been demonstrated in growing excised roots.

“A correlative diurnal rhythm in respira- tion rate has likewise been demonstrated in grow- ing excised roots (White, 1942, 37, 38).”

• cites White, 1942, 37, 38 sourceNot checked — no full text of the source

In studying living, growing organisms, destruction of the material is a serious drawback because it prevents making subcultures from examples that prove especially favorable.

“In studying living, growing organisms, this is a seri- ous drawback, since it prevents the making of sub- cultures from examples which prove to be espe- cially favorable.”

Materials of this degree of variability cannot be treated as individuals but must be treated statistically.

“It is obvious that materials of this degree of variability cannot be treated as individuals but must be treated statistically.”

Powers of adjustment may be enhanced or reduced according to existing conditions as regards other environmental variables with which they have no apparent connection.

“These powers of adjustment may be enhanced or reduced according to the existing conditions as regards other variables in the environment with which they have no apparent connection.”

Increase in protein nitrogen is the best measure of increase in living material available.

“Increase in protein nitrogen is the best measure of increase in living material available.”

The crown gall tissues grown in tissue culture were shown to be free of bacteria.

“The tis- sues were shown to be free of bacteria.”

With plant tissue cultures, the method of imposing or modifying gradients is a virgin field except for White's preliminary observations on oxygen gradients and differentiation and, in a sense, those of Nobecourt and Gautheret on bud formation.

“With plant tissue cultures it is a virgin field except for White's preliminary observations on oxygen gradients and differentiation (Figs.68, 71) (1939, 333, 1942, 334) and, in a sense, those of Nobecourt (1939, 448) and of Gautheret (1940, 286-288) on bud formation.”

• cites White (1939, 333, 1942, 334) sourceNot checked — no full text of the source
• cites Nobecourt (1939, 448)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Gautheret (1940, 286-288)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Measurements recording only the linear increment of the central axis give an accurate record of increase so long as the culture does not branch.

“Measurements which record only the linear increment of the central axis will thus give an accurate record of the increase, so long as the culture does not branch.”

The error from ignoring branches is proportional to the number and importance of the branches present.

“It will be in error in proportion to the number and importance of the branches pres- ent.”

In such tissue cultures, these viruses produce no macroscopically visible symptoms.

“Here they produce no macroscopically visible symptoms.”

When applied to root cultures, a modification using linear rather than area increments as a criterion of growth has furnished the most generally satisfactory measure of increase yet devised.

“When applied to root cultures, however, a modi- fication of this method, using linear rather than area increments as a criterion of growth, has furnished the most generally satisfactory mea- sure of increase yet devised.”

The range around these optima that still permits normal growth is in almost all cases about the same magnitude, from about 0.5 to 5.0 times the absolute optimal value.

“the range around these optima which will still permit normal growth is in almost all cases of about the same magnitude, from about 0.5 to 5.0 times the absolute optimal value (White, in press”

• cites White, in pressNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Lewis and McCoy used a primitive organ-culture technique in the study of bacterial nodule formation on roots of legumes.

“Lewis and McCoy (1933, 301) used a primitive sort of organ-culture technique in the study of bacterial nodule formation on the roots of legumes.”

• cites Lewis and McCoy (1933, 301) sourceNot checked — no full text of the source

If dry weight samples are taken when cultures are growing actively, this may give a fairly accurate indication of protoplasmic activity.

“If samples for such determination are taken when the cultures are growing actively, this may give a fairly accurate indication of protoplasmic activ- ity.”

Viruses that cause a high degree of local injury and have a slow migration rate in the tissue are somewhat more difficult to maintain in culture.

“Viruses which cause a high degree of local injury and which have a slow migration rate in the tissue are somewhat more difficult to main- tain in culture.”

The second objection to the area method is valid when areas of callus cultures are under investigation, since these ordinarily develop as somewhat flattened hemispheres of tissue.

“The second objec- tion is valid when the areas of callus cultures are under investigation, since these ordinarily develop as somewhat flattened hemispheres of tissue.”

In the study of morphogenesis, tissue culture methods provide a means of isolating cells, organs, and tissues from morphogenetic influences of neighboring cells, organs, and tissues and placing them in controlled environments.

“In the study of the origin of form and function, that is, of morphogenesis, tissue culture methods provide a means of isolating cells, organs, and tis- sues from the morphogenetic influences of neigh- boring cells, organs, and tissues and placing them in controlled environments.”

White has shown that an oxygen gradient may be correlated with the response by which undifferentiated callus cultures are induced to form stems and leaves without the intercession of a caulocaline.

“White (1939, 333) has shown that an oxy- gen gradient may be correlated with the response by which undifferentiated callus cultures (Figs.17, 18, 61, 65) are induced to form stems and leaves without the intercession of a caulocaline (Figs.68, 71).”

• cites White (1939, 333) sourceNot checked — no full text of the source

Since normally growing roots seldom produce branches in great number or of great length, the error introduced by ignoring branches will seldom be great.

“Since normally growing roots seldom pro- duce branches in great number or of great length, the error introduced in this way will seldom be great.”

In experiments using 20 replications in each experimental complex, differences of 30 per cent and over can generally be relied on to indicate a true difference in behavior and not merely fortuitous differences due to variability.

“This analysis indicates that in experiments car- ried out in this way and using 20 replications in each experimental complex differences of 30 per cent and over can, in general, be relied on to indi- cate a true difference in behavior and not merely fortuitous differences due to the variability of the”

At concentrations just exceeding the threshold for growth retardation, indole acetic acid causes characteristic shortening and thickening of the root axis, crowding branch primordia into a small space.

“at concen- trations just exceeding the threshold level for growth retardation, a characteristic shorten- ing and thickening of the root axis, resulting in a crowding of the branch primordia into a relatively small space”

• cites Leonian and Lilly, 1937, 219 sourceNot checked — no full text of the source

With the precaution of keeping one needle or loop in boiling water at all times during transfers, bacterial or fungus contaminations are almost never carried from one flask to another.

“With this precaution, bacterial or fungus contamina- tions are almost never carried from one flask to another(Figs.29,30).”

Respiratory activity of plant tissue cultures has been studied in only a single piece of work, on callus cultures of Salix capraea by Plantefol in co-operation with Gautheret.

“This has been done, to date, in only a single piece of work, carried out on callus cultures of Salix capraea by Plantefol (1938, 256, 257) in co-operation with Gautheret.”

• cites Plantefol (1938, 256, 257)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

If all constituents except protein are set aside and protein increase or decrease is followed, this gives about as good a measure of increase or decrease in living substance under a given set of conditions as is at present available.

“if we set aside all con- stituents of an organism except protein and fol- low the increase or decrease in this one constitu- ent, we have about as good a measure of the increase or decrease in living substance under a given set of conditions as is at present available.”

Diseases that cause only moderate local injury and move rapidly into all parts of the host can be maintained indefinitely in tissue cultures without difficulty and without essential change in methods.

“Dis- eases which cause only moderate local injury and which move rapidly into all parts of the host can be maintained indefinitely in tissue cultures with- out difficulty and without essential change in the methods.”

The first objection to the area method does not apply to plant cultures, since no migration takes place from plant tissues.

“The first objection does not apply to the use of this method for plant cultures, since no migration takes place from plant tissues.”

Linear increment measurement has furnished a very satisfactory criterion of growth.

“This has thus furnished a very satisfactory criterion of growth.”

The tendency towards differentiation of scalariform cells in the interior of callus cultures may be looked upon as an example of cellular response to a particular environmental complex, in this case one of low available oxygen content.

“The tendency towards differentiation of scalariform cells in the interior of callus cultures (White, 1939, 78) may be looked upon as an example of cellular response to a par- ticular environmental complex, in this case one of low available oxygen content”

• cites White, 1939, 78 sourceNot checked — no full text of the source

The tissue culture technique has been applied to study reactions of tissues, organs, and cells to variations in concentrations of nutrient materials, growth stimulants, toxins, and other environmental variables.

“The tissue culture technique has been applied to the study of the reactions of tissues, organs, and cells to variations in concentrations of nutrient materials, growth stimulants, toxins, and other environmental variables.”

Gautheret, Dauphine, Robbins and colleagues, and Addicott have utilized root cultures for anatomical and histological studies.

“Gautheret (1935, 15, 1937, 282, 1938, 283, 284, 1940, 286-289), Dauphine (1930, 279), Bobbins and bis colleagues (Bobbins and V. B. White, 1936, 62), and Addicott (1941, 196) have utilized root cultures for some anatomical and histological studies.”

• cites Gautheret (1935, 15, 1937, 282, 1938, 283, 284, 1940, 286-289)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Dauphine (1930, 279)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Addicott (1941, 196) sourceNot checked — no full text of the source