142 BOTANICAL GAZETTE [august 



from each of the potential megaspores arising from the inner hetero- 

 typic daughter cell. 



The binucleate cell arising from the homoeotypic division in the 

 inner (heterotypic) daughter cell enlarges greatly by vacuolization, 

 and by two further nuclear divisions forms the 8-nucleate embryo 

 sac (figs. 36, 37). After a period of growth, a typical egg appara- 

 tus and an antipodal group are organized. The polar nuclei fuse 

 and the fusion nucleus takes up a position close to the egg. 



Medeola virginica 



The very large megaspore mother cell of Medeola virginica is 

 in many cases hypodermal. Fig. 38 shows a very common condi- 

 tion in which the mother cell in synapsis lies in contact with the 

 epidermis. 



Although a conspicuous cell plate is formed at the time of the 

 first division of the nucleus of the mother cell (fig. 39), it does not, 

 so far as I can determine, result in the formation of a division mem- 

 brane. It entirely disappears before the homoeotypic division. 



The outer heterotypic nucleus divides slightly in advance of the 

 inner, and temporary cell plates are formed between each pair of 

 nuclei (fig. 40). These cell plates persist for some time, often being 

 visible after the third division of the mother cell (fig. 43). 



The daughter nuclei resulting from the division of the inner 

 heterotypic nucleus may be equal in size (fig. 40) or they may be 

 very unequal (fig. 41), the innermost nucleus being much smaller 

 than the outer. In several cases, in fact, the inner nucleus ap- 

 peared so shrunken and disorganized as to be very probably inca- 

 pable of further division (fig. 42). Such a condition would cause 

 embryo sacs with but 2 antipodal cells, and it seems very probable 

 that this is occasionally the case. 



Frequently the small inner nucleus divides at the time of the 

 division of its larger sister nucleus, the result being 2 large and 2 

 small nuclei. One of the large nuclei is a polar nucleus, and the 

 other, with the 2 small nuclei, forms the 3 antipodal nuclei (fig. 43)- 

 In still other cases, where the division of the inner heterotypic 

 nucleus has been such as to form 2 nuclei of equal size, 3 uniform 

 antipodal nuclei are formed (tig. 44). 



