447 
Mnium affine, var. ciliar is (Grev.), C.M. 
across the cell. By this time the daughter-nuclei have returned to approxi¬ 
mately the condition of prophase shown in Figs, 2 and 3. During these 
stages as represented in Figs. 4, 5, and 6, no lumps, cytoplasmic plates, or 
polar bodies of any sort could be detected in the cytoplasm, and the cells 
seemed to be perfectly fixed and were very carefully stained. 
The Androcyte and its Development into the Mature 
Sperm. 
The first evidence that the last division of the spermatogenous tissue 
has occurred is the rounding off of the cells (Figs. 7, 8, and 9) and the 
appearance near the periphery of the cell of a densely staining body, 
the blepharoplast (Fig. 10). As was stated above, the last division of the 
spermatogenous tissue is not diagonal, so that frequently antheridia are 
found crowded full of such cells as are represented by Figs. 7, 8, and 9, but 
quite often more angular in outline than these figures. The cells apparently 
do not noticeably round off or separate from each other until this last 
division is complete. The tissue from which Figs. 3, 4, 5 ? an d 6 were 
drawn was evidently undergoing this division as the cells were beginning to 
separate and round off slightly. Only in cells which have become free from 
each other have I found the development of the dark body, the blepharo¬ 
plast, shown in Fig. 10. In the earlier cell generations of the antheridium 
no such body was discovered. The evidence obtained here in regard to this 
body points to an origin similar to that which the author has previously 
suggested for Blasia, Porella , and other Liverworts. In Blasia (8) the first 
indication of the blepharoplast is a dense area of cytoplasm. A definite 
granule is differentiated apparently in this dense area and develops as 
a homogeneously staining thread or cord around the cell near the plasma 
membrane. A similar process obtains in Mnium (Figs. 11 and 12). The 
nucleus takes up a position to one side of the cell, so that as the blepharo¬ 
plast grows in length the latter comes in close contact with the nucleus. 
For some time the blepharoplast may be observed as distinct from the 
nucleus ; then the two seem to become more or less fused together. It is 
during this stage of development that the most varying accounts have been 
given. It seems to me not surprising that such has been the case. At 
a time like this, when protoplasmic structures are changing so rapidly, 
slight differences in the methods of handling the material or differences 
in growth conditions at the time of fixation may very greatly alter the 
appearance of certain parts. Walker ( 5 ) has called attention to the extreme 
sensitiveness of such cells as these to changes in the environment. As 
I have already suggested, these facts should at least be kept in mind 
by any one investigating this stage of development. 
Although Wilson (6) and Walker ( 5 ) agree that, as the nucleus takes 
up its final position and changes to the form found in the mature sperm, the 
