THE FEMALE GAMETOPHYTE 



73 



reduced number of chromosomes, and this is true whether a row 

 of two, three, or four megaspores is to be produced, or the 

 mother-cell is to develop directly into the embryo-sac, as in 

 Lilium. In such forms as Lilium the second mitosis also corre- 

 sponds in all essential details with the second division that is to 

 result in a row of four megaspores. The third mitosis differs 







B 



Fig. 29. — A, Canna indica ; axial row of four megaspores, the innermost one beginning 

 to germinate and the other three disintegrating; after Wiegand.™ £, Eichhornia 

 crassipes : portion of nucellus showing four megaspores, the innermost one germi- 

 nating, and the other three, which are not separated by wails, disintegrating; 

 x 1100 ; after Smith." 



from the usual sporophytic mitosis only in the reduced number 

 of chromosomes (Miss Sargant, 41 Strasburger, 72 Juel 88 ). Not 

 only do the first two divisions agree in the various types, but 

 they correspond minutely with the two divisions with which 

 the microspore mother-cell gives rise to the tetrad. That the 

 megaspores do not occur in tetrahedral or bilateral arrange- 

 ment does not involve their morphological nature, for in the 



