of Fertilization in Angiosperms . 707 
endosperm-nucleus at all. In other cases where the endo¬ 
sperm resembles the male parent in certain parts only, he 
supposes the second generative nucleus to have divided 
independently. 
It would certainly be desirable to have independent evidence 
that the triple fusion normally takes place in Zea Mays . Until 
such has been obtained I think we may assume that it does so. 
It has been shown earlier in this paper that the mass of 
evidence for its general occurrence among Angiosperms is 
considerable. Dr. Webber’s views, though quite tenable, 
hardly seem justified by his observations (as quoted in ‘ Nature ’), 
for we know how capricious the facts of heredity appear in 
particular cases. The balance of probability, as of authority, 
seems to me to be in favour of regarding the paternal endo¬ 
sperm characters as derived from the presence of a male 
element in the primary endosperm-nucleus. 
Returning to the question in hand, we have found that the 
nuclear fusion under consideration resembles a sexual union 
in containing a normal male and female element, and differs 
from it in including a third nucleus which in some cases is 
built up of at least twice as many chromosomes as either. 
The result of this fusion is a body which often resembles the 
product of fertilization in exhibiting a mixture of parental 
characters, but is unlike such a product in form and life- 
history. Whether we shall call such a fusion a true act of 
fertilization or not depends chiefly on our theoretical con¬ 
ception of the process of fertilization, and the definition of the 
act of fertilization which w r e choose to adopt. Authorities 
have already differed on this point. Before discussing the 
grounds on which they base their respective views, I wish to 
make a suggestion as to the meaning to be attached to the 
presence of a third nucleus. 
The observations already quoted on polyspermy in the sea- 
urchin have shown that the union of more than two nuclei 
in the sexual act commonly produces monstrous forms. 
Groom (22) has shown that fusions of two or more asexual 
nuclei among Fungi often led to the production of degenerate 
