Diagram of Three Stages, A, B and C, in the Growth of a 

 Feather. 



1, horny layer of epidermis ; 2, gerniinative layer of epidermis ; 3, dermis which iovw 

 a papilla at 3^ : 4, follicle containing feather ; 5, young feather ; (i, blood-vessels. 



P.^- 



P.f. 



.?&8^4lB-*>^*?<^^'=^'^4.€ 







5t.«^»J 





ent. 



meso. 



Fig. 57 



Transverse Section through the Primitive Streak. 



p.g., primitive groove ; p.f., primitive fold ; ect., ectoderm ; ent., entoderm 

 meso., mesoderm. 



