THE DEVELOPMENT OF VERTEBRATA. 299 



13. Give a brief explanation of each of the following 

 terms: (1) primitive streak; (2) Graafiau follicle; (3) 

 blastopore ; (4) protovertebrso ; (5) female pro-nucleus. 



14. Give an account of the developmental origin and the 

 structure of the notochord and (in the last three) of its 

 relations to the vertebral centra in Amphioxus, the dog- 

 fish, the frog, and the rabbit. 



15. Describe the egg, the process of fertilization, and the 

 formation of the germ-layers in the rabbit, fowl, frog, 

 and Amphioxus. 



16. Give an account of the first appearance and de- 

 velopment of the amnion and of the allantois. In what 

 animals do they occur ? What appear to be their functions? 



17. Describe and compare the egg of the fowl and 

 rabbit, and give an account of their mode of fertilization 

 and early developmental changes. 



