GYMNOSPERMS. 155 
which is in contact with one end.of the blepharoplast in the earlier 
part of its development (Fig. 63, A). 
The mature spermatozoid is also quite similar in structure to that of 
Cycas, consisting of a large nucleus completely surrounded by a layer 
of cytoplasm in which the ciliferous band, or blepharoplast, is located 
just beneath the plasma membrane. The blepharoplast is in the form 
of a helicoid spiral, making about five or six turns counter clock-wise 
and embracing about one-half of the body of the cell (Fig. 65, B). 
The spermatozoid, as in the ferns, is a transformation of the entire 
cell and, therefore, a true spermatozoid. 
The development of the spermatozoid in Gzzkgo according to Hirase 
(’98) is quite similar to that in Cycas as described by Ikeno. In the 
generative cell of Gézkgo Webber (’97) and Hirase (’98) find that, 
when the nucleus becomes strongly flattened or lenticular, a large 
nucleolus-like body appears on either side of the nucleus between the 
nuclear membrane and the young blepharoplasts. Other similar but 
smaller bodies are sometimes present in the cell, Accompanying these 
two bodies Hirase finds coarsely granular cytoplasm. The bodies in 
question react toward stains much as do nucleoli, and, since they dis- 
appear at a later stage, it is probable that they represent merely extra- 
nuclear nucleolar substance. 
Miyake (’o2) finds that after the division of the generative cell in 
Ginkgo a cell-wall is formed between the two daughter-cells, and that 
a distinct and firm wall was always found around the two spermato- 
zoids. The fact that a wall is or is not formed about the daughter- 
cells, z. e., the mother-cells of the spermatozoids, does not affect the 
morphological rank of the spermatozoid. 
The mature spermatozoid of Zamza is probably the largest male 
gamete known in the plant kingdom, being plainly visible to the 
unaided eye. When swimming freely and without pressure it is 
slightly ovate, nearly round or compressed spherical (Fig. 65, B). 
They vary greatly in size, however, ranging in length from 222 to 
332 #, and in width from 222 to 306 p. 
Ikeno describes the spermatozoid of Cycas as being provided with 
a tail which is merely the elongation of the posterior part of thé cyto- 
plasmic mantle. Measured in sections the length was found to be 160 p 
and the width 70 ». The length of the tail was So » or equal to that 
of the body. Fujii has shown that the tail attributed to the spermato- 
zoid of Ginkgo was an artifact, and this statement has been confirmed 
by Miyake. Since no tail exists in Zama, it is probable that that 
described for Cycas may also have been the result of abnormal 
conditions. 
