THE HABITS AND DEVELOPMENT OF THE 

 NEWT {Diemyctylns viridescens). 



EDWIN O. JORDAN. 



TABLE OF CONTENTS. 



Page 



Introduction "7° 



I. Natural History -7° 



1. Habitat -70 



2. Food "7 ^ 



3. Spermatophores -73 



4. Receptaculum seminis 274 



5. Egg-laying '■ ^75 



6. Transformations ^79 



II. Maturation of the Ovum 280 



1. Technique 2^° 



2. Origin and developme7it of the ovum as a whole 282 



3. Yolk-nucleus -"^4 



4. Yolk formation -9^ 



5. Germinal vesicle as a whole 294 



6. Nucleoli 296 



7. Chromosojnes -99 



8. General considerations 3°° 



9. Atrophy of the germinal vesicle and formation of the polar bodies.... 301 



III. Fertilization 309 



1. General phenomena 3°9 



2. Polyspermy 3^5 



IV. Cleavage 3^9 



V. Formation of the Blastopore 3^5 



1. Technique 3^5 



2. Segmentatiott cavity Z'^7 



3. External appearances 3^8 



4. Invagination 3-^^ 



VI. Fate of the Blastopore 334 



1. Method of closure of the blastopore 33^ 



2. Neuropore and anus 34° 



3. Primitive streak 34' 



VII. Germ-layers and Notochord 347 



1. Germ-layers 347 



2. Notochord 35^ 



269 



