Experimental studies on germinal localization

Abstract

Introduction.Preliminary Observations on the unsegmented Egg and the normal Effect of removing the Polar Lobe.DeveIoprncnt.( a ) General history of the loheless Embryo, with a Coinparison of (b) The Mesoblast Question.Region.( a ) Development of Fragments obtained by horizontal or oblique Sec-(b) Development of Fragments after vertical Section.isolated Polar Lobe.isolated Blastomeres.Localization of the apical Organ, and its Correlation with the post-trochal Localization in the unsegmented Egg.tion.Observations on enucleated Fragments of fertilized Eggs and on the Comment.Summary.INTRODUCTION.The following experimental studies are offered as a contribution to the theory of "Organbildende Keimbezirke" or germinal prelocalization, especially as applied to the cytoplasmic regions of the unsegmented egg.Following the enunciation of the principle of "precocious segregation" by Ray Lankester, in 1877, the im-1This work was carried out at the Naples Zoological Station between February and August, 1903, on a grant from the Carnegie Institution of Washington, in which was included the use of one of the tables subscribed for by the Institution.My best thanks are due to the administration of the station for the unfailing efficiency and courtesy with which my work was aided in every possible way.