of Some Embryo-sacs. 83 



dividing first (Plate XI, Fig. 6). The inner quadri-nucleate 

 cell now becomes passive and after a time undergoes a slow 

 degeneration, which becomes complete about the time of 

 fertilization. 



After a short resting phase the quadri-nucleate embryo-sac 

 grows rapidly, and by the degeneration of the three cells first 

 formed from the archcsporium, as well as the surrounding 

 nucellar cells, it comes to lie against the epidermis of the 

 nucellus. By division of each of its nuclei, the quadri-nucleate 

 embryo-sac at length shows eight nuclei. The eight nuclei 

 of the embryo-sac now arrange themselves in the typical 

 manner (Fig. 7). By the time the embryo-sac has become fully 

 developed the ovule has become completely anatropous, and 

 the primine and secundine have grown so as to completely 

 cover in the nucellus. 



The question now arises as to the nature of the quadri- 

 nucleate cell next the embryo-sac. For some time it appeared 

 to the writer that this cell might represent a sporocyte which 

 had divided into four spores. Accordingly if such were the 

 case, one would be led to suppose that the embryo-sac repre- 

 sented two sporocytes which were not separated by a cell 

 wall. This view seemed to find some support in the observa- 

 tion by Mann of a partition wall in the embryo-sac of Myosu- 

 rus, and in the possibility of the fertilization of the synergids 

 as described by Dodel and Overton in Iris and Lilium. A 

 more careful study of its relationship, however, seems to 

 militate against the hypothesis that the embryo-sac contains 

 two sporocytes. In its development, the Angiospermic 

 embryo-sac agrees, on the whole, pretty closely with that of 

 Gymnosperms. Further, the reduction division, which so far 

 has been found to take place during spore formation, appears 

 to occur in the formation of the embryo-sac and its neighbor 

 quadri-nucleate cell. Accordingly it seems probable that the 

 quadri-nucleate cell is an embryo-sac or macrospore which 

 only goes part way in its development. 



