42 SPERMATOGENESIS AND FECUNDATION OF ZAMIA. 
division approaching metaphase and the spindle is mainly formed. It 
is highly important to understand the details of spindle formation, 
because further light might be thrown on the nature of the blepbaro- 
plast, but the writer has not been able as yet to find the necessary 
intermediate stages to make the process clear. 
In the next stage which has been observed the spindle is in an 
advanced stage of formation and the chromatin matter has become 
contracted to the center of the nucleus (fig. 31). The nuclear mem- 
brane is still intact throughout, the spindle being entirely intranuclear. 
The spindle fibers which are plainly visible do not as usual draw 
together at the poles and form a sharp-pointed spindle, but in this 
stage form a blunt-poled or barrel-shaped spindle, something similar 
to that described by Fairchild in Basidiobolus (31, figs. 3 to 6). Certain 
groups of fibers can be seen to be attached to certain chromosomes 
and extend in a well-differentiated bundle toward the pole, reaching in 
this stage to the nuclear membrane, which is still apparently intact 
throughout, being as plainly visible at the poles as in any other region. 
This would point to the nuclear origin of the spindle, though it is of 
course possible that. the kinoplasmic filaments surrounding the blepha- 
roplast could have penetrated into the nucleus and served to form the- 
spindle. This, however, is not thought to be the case, although it may 
be remarked that the radiations from the blepharoplast, which were so 
striking in the early stages of development, are not nearly so promi- 
nent in this stage. The intranuclear origin of the spindle, while not 
of common occurrence, is nevertheless found in some instances among 
plants, as in the case of Valonia, described by Fairchild (80, p. 336), 
and Ascophyllum, described by Farmer and Williams. The latter 
authors say: : 
An interesting feature presented by the achromatic spindle in this, and especially 
also in the following oogonial divisions, as well as in the divisions of the oospore, 
lies in the fact that it is largely intranuclear. It begins to be formed before the 
nuclear wall can be seen to be broken down at the two ends * * * (37, p. 625). 
In this stage of the division of the central cell in Zama the nucleolus 
has already entirely disappeared. The nucleus has the shape of a 
biconvex lens, being almost elliptical in section, its minor axis cor- 
responding usually to the major axis of the cell (fig. 31). The spindle 
does not occupy the entire nucleus, and at each side the protoplasm 
retains the reticular form similar to its structure before the spindle 
beean to form. The most noteworthy variation in structure occurring 
in the cell at this stage of the division is in the blepharoplast, which 
has undergone a striking change since the last stage. It has increased 
in size somewhat, and the outer membrane has separated from the 
contents, which in the meantime has shrunken somewhat, though not 
very markedly as yet. The outer membrane of the blepharoplast 
stains more deeply purple with Flemming triple stain, and has sepa- 
