30 SPERMATOGENESIS AND FECUNDATION OF ZAMIA. 
tinct membranes (fig. 19). The plasma membrane delimiting the cells 
in this case stain the same and appear the same in all noticeable char- 
acters as the membranes in other portions of the same cell and of the 
central cell. 
APPEARANCE AND GROWTH OF BLEPHAROPLASTS. 
After the division of the second prothallial cell into the stalk cell 
and central cell the entire apparatus continues to grow in size, and the 
next important stage of development following this is the appearance 
of the blepharoplasts.’' 
In order to determine the true nature of the blepharoplast it was 
necessary to know its history, and a very careful study has been made 
of its first appearance and gradual development. They were first dis- 
covered by the writer in Zama in a medium stage of development, as 
shown in figures 26 and 58, in which stage they present a very striking 
appearance and would be taken for undoubted centrosomes. Similar 
organs occur in the central cell of Ginkgo biloba, and were first 
described by Hirase in 1894 (57). Hirase simply described their 
appearance in a half-grown stage, without tracing out their origin and 
function. They were next described by the writer in Zama in 1897 
(122, 123, and 124), and here their gradual growth and development 
into the cilia-bearing organ of the spermatozoid was traced. It was 
further found that they had no intimate connection with fecundation, 
being left at the apex of the egg cell while the nucleus passes on alone 
and fuses with the egg nucleus. 
Not being able to obtain material of Zama in 1897 to trace out the 
origin of the blepharoplasts, the early stages of Ginkgo were studied, 
and it was found that here they were formed de novo in the cytoplasm 
of the central cell. In 1898 the same organs in Cycas revoluta were 
carefully described by Ikeno (70). Since publishing his results in 
1897 the writer has made a very careful study of the early stages in 
Zamia, and finds that here also they originate de novo in the cytoplasm 
of the cell, as first described by him in Ginkgo. 
During the division of the second prothallial cell as pointed out 
above (fig. 17), no indication of any organ resembling a blepharoplast 
or centrosome could be discovered at the pole of the spindle. The 
difficulty of obtaining this cell in stages of division, however, has pre- 
vented a very thorough examination at this stage. After the division is 
completed in stages like that represented in figure 18 and slightly later, 
avery careful examination fails to reveal a trace of any organ which 
could be considered to be an early stage of the blepharoplast. When 
1A term applied by the writer (124, 1897), to the cilia-forming organ of the 
spermatogenous cells of Zamia and Ginkgo which so nearly resembles a centrosome or 
centrosphere. The term isderived from 6Aegaprs, eyelash or cilium, and zAa6ros, 
formed. 
