1887] The Significance of Sex. 225 
macrogonidia and microgonidia to each other. In Limax the 
microsomata are approximately equal in number in the two pro- 
nuclei; and as the result, so far as fertilization is concerned, is the 
same in the two animals, we must believe that the pronuclei need 
not be morphologically equal. It has been said that the two 
parents furnish equal contributions of hereditary characters be- 
cause the chromatin is alike in amount in the two pronuclei. But 
this assumes that quality depends on quantity. We cannot accept 
this notion. We believe the quality of the chromatin inheres in 
the nature of each gemmule, that the gemmules are nearly alike, 
and that the quantity of chromatin may readily be increased by the 
multiplication of the gemmules. Such multiplication may take 
place in the male pronucleus before fusion because of the nutri- 
tive conditions furnished by the yelk. Even if it did not increase 
in this way, it might happen that the reproductive vigor of the 
fertilizing gemmules is so great that during ontogeny they would 
at last outnumber the ovum gemmules. We do not know 
whether characters are realized in proportion to the number of 
the gemmules, or whether it depends on the strength of the 
gemmules, or, again, on some dynamic influence reciprocally 
acting between the gemmules. In the last supposition we might 
have each gemmule possessing a system of vibrations whose 
wave-form could be slightly altered by the proximity of differing 
systems ; and that, finally, equilibrium being established, it would 
require a new fertilization to introduce a new variation. It would 
also be intelligible how gametes may develop parthenogeneti- 
cally before fusion is accomplished where only the preliminary 
steps to such end have been taken. Finally, such variation could 
be effected by other means than by fertilization. 
Under the first supposition we could understand how, if cell- 
division should not succeed in separating the gemmules in due 
proportions, we might get cells that had a preponderance of 
gemmules of one ancestor, and the parts of the body developed 
from the offspring of these cells would present the characters of 
one parent to the exclusion of the other. But we defer the 
discussion of this point to the subject of heredity. 
Strasburger claims that fertilization is effected by the fusion 
of similar parts in two cells, cytoplasm with cytoplasm, nucleus 
with nucleus, and nucleolus with nucleolus. But in phanerogams 
it is only nuclei that migrate from the pollen-tube to fuse with 
