566 - THE AMERICAN NATURALIST. (Nor: XXXIX. 
the single fusion nuclei within these reproductive cells. There 
is much evidence that the period in the life history characterized 
by the presence of paired nuclei represents a sporophyte phase. 
Blackman (:04a, p. 353) regards the process by which the 
second nucleus enters the “fertile cell,” resulting in the conju- 
gate nuclei, as a reduced form of ordinary fertilization. I have 
already pointed out in Section IV, “ Asexual Cell Unions and 
Nuclear Fusions,’’ what seem to me to be serious objections to 
the use of the term fertilization when it is clear that the second 
nucleus in the pair is morphologically not a gamete nucleus, and 
the subject was also taken up in the account of fertilization in 
the present section. Whatever may be the physiological inter- 
pretation of this remarkable phenomenon it seems to me clearly 
a substitute process for a former sexual condition and involves 
other elements than the original gametes and as such, is a typi- 
cal illustration of apogamy. 
It seems probable that further studies in the Basidiomycetes 
will determine a similar origin for the paired nuclei preceding 
the basidium to that of Phragmidium but without any trace of 
former sexual organs at least in the higher groups. And these 
conditions must signify the complete disappearance of structures 
representing sexual organs and the substitution of an apogamous 
development of the sporophyte generation for the sexual act. 
In this connection the interesting nuclear fusions in the ascus 
are of great interest for they may hold relations to degenerate 
sexual conditions in the Ascomycetes. 
Farmer, Moore, and Digby (:03) have reported some remark- 
able nuclear fusions preceding the apogamous development of 
the sporophytes of Nephrodium, which have many points of 
resemblance to the apogamous phenomena in the Uredinales 
just described. These authors find that cells of the prothallus 
from which the sporophytic outgrowths arise, become binucleate 
through the migration of nuclei from neighboring cells. The 
two nuclei may remain separate for some time or they may fuse 
at once. They regard the whole process **as a kind 'of irregu- 
lar fertilization" by which the outgrowth destined to form the 
sporophyte becomes supplied with nuclei containing the double 
number of chromosomes. It seems to me unfortunate to asso- 
