158 ARCHEGONIATES. 
able, judging from the karyokinetic figures observed, that the nuclear 
division leading to the formation of the ventral canal-cell is of the 
heterotypic type, and takes place essentially as in the first division of 
the pollen mother-cells of the Z7/éacee. This is certainly an error, 
for in both Gymnosperms and Angiosperms the heterotypic nuclear 
division occurs in the micro- and macrospore mother-cells and nowhere 
else in ontogeny. Since the spore mother-cells of the Gymnosperms 
are homologous with those of the higher plants, we naturally expect 
to find the heterotypic division in Cycas in the first karyokinesis of 
the macrospore mother-cell. This is made all the more certain by the 
researches of Juel (1900), who finds in Zerzx that the first nuclear 
division in the macrospore mother-cell is heterotypic. In ZLarcx and 
Fre. 65.—Upper end of nucellus ; spermatozoids in pollen tube of Zamza.—(After Webber). 
A, diagrammatic outline of upper end of nucellus, showing proximal ends of pollen tubes growing down 
into the cavity just above archegonia; a, archegonia; J, prothallium; dc, pollen chamber ; Z/, pol- 
len tubes; fg, pollen grain. 
B, two mature spermatozoids in proximal end of pollen tube. 
in other Gymnosperms the earlier development of the macrospore is 
precisely the same as in such Angiosperms as Aedleborus, in which 
the first nuclear division is heterotypic and homologous with the first 
division in the pollen mother-cell. 
The formation of the ventral canal-cell may represent some sort of 
a maturation process, and the conclusion that this cell is an aborted 
egg is tempting, but at our present state of knowledge such an infer- 
ence is scarcely justifiable. 
FECUNDATION. 
Soon after its formation the ventral canal-cell disorganizes. The 
nucleus of the egg passes back gradually toward the middle of the cell, 
at the same time increasing in size. Finally, when the center of the 
cell is reached, the nucleus is usually large, being generally longer 
than broad, and shows the structure of the resting condition, 
