1907] 



PACE-FERTILIZATION IN CYPRIPEDIUM 



365 



Successive stages 

 in maturation of 

 animal egg, and in 

 development of 

 megaspores in Cypri- 

 pedium 



and 



in 



Lilium. A, the di- 

 vision of the primary 

 oocyte to form the 

 first polar body (p^) 

 and the secondary 

 oocj^e; and the di- 

 vision of the mother 

 cell in Cypripedium 

 and in Lilium — all 

 heterot}^ic divisions. 

 B, the division of the 

 secondary oocyte to 

 form the second 

 polar body (/»») and 



the 



and the 



m 



egg; 



second division 

 Cypripedium and in 

 Lilium, giving the 

 megaspores (m) — the 

 homotypic division 

 in all. C, the same 

 stage as the preced- 

 ing, but the first 

 polar body of the 

 animal and the 

 micropylar nucleus 

 of Cypripedium di- 

 viding. D, the egg 

 and the three polar 

 bodies {p) of the 

 animal, and the 

 megaspores {m) of 

 Cypripedium and of 

 Lilium. Ey not in 

 the animal series; 

 the di\'ision that 

 gives the egg in 

 Cypripedium and in 



Lilium. ^ 



Animal 



Cypripedium 



Lilium 



-O-^...., 



B 



D 



E 



