698 Sargant.—Recent Work on the Results 
possible, the attention of the investigator is led to critical 
observations which may decide between them. His powers 
are directed to clearing up certain obscure points one after 
the other, and so step by step he wins his way to the truth. 
But any one of these explanations, if received too hastily as 
representing facts, will be fatal to research. Each may 
become the watchword of a school, and arouse fruitless con¬ 
troversy. It is therefore with no idea of coming to any 
decision in favour of one view rather than another that I 
propose to discuss the suggestions already made as to the 
homologies of the cells derived from the Angiospermous 
embryo-sac. I would rather ask what line of research is 
suggested by the work of the last decade in this direction, and 
in particular what change in theoretical conceptions has arisen 
from the discovery of double fertilization. 
We have recently been learning by degrees that the struc¬ 
ture of the embryo-sac in Angiosperms is by no means so 
uniform either before or after fertilization as botanists were 
once apt to believe. Some of these variations are undoubtedly 
derived from the more usual structure, and are specialized for 
some particular end, rather than primitive. Thus the persis¬ 
tence and occasional division of the antipodal cells in Nigella 
sativa described by Westermaier ( 44 , p. 8), is probably due, as 
he suggested, to their function in this plant as transmitters of 
food material. But it would be very rash in the absence of 
further evidence to assume that the multiplication of antipodal 
nuclei in the embryo-sac of Sparganium simplex (Campbell, 
19 , 20 ), must be referred to a similar cause. Westermaier 
himself has described a growth of ‘ antipodal tissue 5 in Zea 
Mays and other Grasses before fertilization. In Sparganium , 
and perhaps in Zea also, the multiplication of cells within the 
embryo-sac cannot but suggest the formation of a prothallus. 
Whether this suggestion is justified can be determined only 
by extended research, 
The antipodal cells have been considered as representing 
(a) the vegetative part of the prothallus, (b) a second egg- 
apparatus, and (c) that part of a monoecious prothallus which 
