364 BOTANICAL GAZETTE [November 



i 



divides and throws off a polar body, and forms the secondary oocyte. 

 The polar body may divide; the secondary oocyte divides, forming 

 another polar body and the mature egg (megaspore) (see Boveri 6 

 and Wilson 47)- The two divisions are of the heterotypic and 

 homotypic types found in plants in the formation of megaspores. 

 In Cypripedium, if the last division in the embryo sac were omitted, 

 there would be the same number of divisions in the formation of the 

 egg as in the animal. If the w^all w^re omitted between the daughter 

 nuclei at the division of the mother cell, as in LiKum, and the last 

 division were omitted, the sac would have four nuclei as now; and 

 this would be true of Lilium if the last division did not take place. 

 This situation was discussed by Chamberlain (il, 12) in connection 

 with the usual eight-nucleate sac, and also in relation to the probable 

 four-nucleate sac of Cypripedium. 



more clear bv means 



Fig. A represents the primary oocyte dividing in the usual way and 

 the mother-cell division in Cypripedium and in Lilium; in all cases 

 this is the heterotypic division. Fig. B represents the next division 

 if the first polar bodv fails to divide, and if the microDvlar nucleus 



Cyp 



same sta^e as fig 



but the first polar body and the micropylar cell in Cypripedium 

 divide; this is the homot}^ic division. Fig, D represents the division 



iig. C completed, with 



in all three forms. 



com 



but in Cypri- 



um 



fig, E. It is e\ident that in these forms there is even greater 



male 



mother cell be taken as the 



SMmm 



Chamberlain 



the male nucleus represents two divisions beyond the microspore 



while in Cypripedium and Lilium the egg is remov 

 division from the megaspore nucleus. 



Wall in pollen grain 



gram 



xp 



according to present homologies. It has been reported in a few 



liver .^6),Naia 



ampbell 8, Q), PoDulus and Lilium 



* 



