142 ARCHEGONIATES. 
able in the sperm-nucleus varies greatly in different individuals. In 
some cases the sperm-nucleus, after two days, showed no further 
advance than was observed in others after only thirty-six hours. As the 
reticulation of the sperm-nucleus continues, its structure becomes looser 
and more open, and its cork-screw shape disappears (Fig. 56, D, E). 
As far as is known at present the reticulation of the sperm-nucleus 
continues until its network is no longer recognizable from that of the 
egg when fecundation is complete. 
During the process of fusion it will be seen that the sperm-nucleus 
goes through the same series of changes as in the development of the 
spermatozoid, but in the reverse order. The time elapsing between 
the entrance of the sperm-nucleus into the egg and complete fusion 
may vary considerably in individual cases. 
In Pilularia globulifera, according to Campbell (’88), the sperm- 
nucleus assumes a loose and more granular structure, and rounds up 
before penetrating or uniting with the nucleus of the egg. Judging 
from Campbell’s figures, it seems that in Osmunda (Campbell, ’92) 
the sperm-nucleus, as in Ozoc/ea, enters the nucleus of the egg before 
undergoing any visible change in form or structure. 
In this respect certain ferns are without parallel in the plant king- 
dom, except, perhaps, in the Gymnosperms, and it would be inter- 
esting to know how widely distributed the phenomenon is in the 
Pteridophyta, and whether it occurs in any other plants. 
GYMNOSPERMS. 
CYCAS, ZAMIA, AND GINKGO. 
THE MALE, GAMETOPHYTE, 
The development of the spermatozoid in Cycas (Ikeno, ’96, ’98), 
Ginkgo (Hirase, ’96, 98; Webber, ’97; Fujii, 1900), and Zamia 
(Webber, ’97, :g01), bears a striking resemblance to that in the fern, 
especially in regard to the origin and behavior of the blepharoplast. 
There seems now to be no doubt that the blepharoplast in these three 
genera is homologous to the blepharoplast of the fern, and, in fact, the 
entire development of both sexual cells indicates with a certainty that 
these gymnosperms bear a close phylogenetic relationship to the 
pteridophytes. 
Since the development of the spermatozoid in Cycas and Zamia 
differs in certain important details according to the two investigators, 
Ikeno and Webber, a somewhat detailed account of the process will be 
given for both genera, while Giz&go will be referred to for comparison. 
