THE GENESIS OF THE PLASMA-STRUCTURE IN 

 THE EGG OF HYDRACTINIA ECHINATA 



CORA JIPSON BECKWITH 



From the Zoological Laboratory, Columbia University 



SIXTY-SIX FIGURES (eIGHT PLATEs) 



CONTENTS 



I. Introduction 190 



II. Review of Schaxel's work 191 



ril. Protoplasmic granules and mitochondira in Hydractinia 193 



A. Material and methods 193 



B. Protoplasmic structure of mature egg 196 



C. History of young egg (bouquet-stage) 198 



D. Early growth-period 199 



1. Nuclear reconstruction 199 



2. Pseudochromatin-granules 199 



3. Basic staining globules 200 



E. Growth and differentiation of adult structures 202 



1. Nucleus 202 



2. Protoplasmic changes 202 



a. Development of simple yolk 202 



b. Development of compound yolk 203 



c. Development of mitochondria 204 



d. Development of oil 205 



F. Discussion and conclusions (nature of the extra-nuclear granules) 206 



1. Morphological evidence 206 



2. Staining tests and experiments 207 



a. Preserved material 207 



b. Intra vitam stains 208 



3. Digestion experiments 212 



4. Various other tests 213 



G. Other accounts of chromatin-emission in hydroids 214 



H. Mitochondria 216 



1. Experiments 216 



2. Discussion and comparisons 218 



a. Origin 218 



b. Relation to yolk and yolk-nucleus 219 



c. Relation to protoplasm 219 



IV. Maturation phenomena and amitosis in Hydractinia and Eudendrium. . 220 



189 



JOURNAL OF MORPHOLOGY, VOL. 25, NO. 2 

 JUNE, 1914 



