Woodbum . — Spermatogenesis in Blasia pusilla , Z. 95 
with similar polar bodies in the corresponding cell generation of Marchantia 
the writer found no radiations extending peripherally. Allen had difficulty 
in tracing this central body through the succeeding phases of karyokinesis, 
but found evidence which he considered sufficient to establish its persistence 
beyond a reasonable doubt. After division is complete a body, the 
blepharoplast, is apparent in the region formerly occupied by the pole of 
the spindle and the central body. So far as the writer has observed in the 
Hepaticae, the first appearance of the blepharoplast occurs in a different 
part of the cell, as will be shown in the following paper. 
It may be of interest to compare these results with those obtained 
from observations on the Blasia pusilla. Antheridial plants were fixed in 
chromic-osmic-acetic acid at intervals during the month of July. The 
material, after fixing ordinarily for about twenty-four hours, was washed, 
brought up through the various grades of alcohol, embedded, and sectioned 
from 2 to 4 microns thick. Anilin safranin and gentian violet were used as 
stains, and also Heidenhain’s iron alum-haematoxylin counterstained with 
Bismarck brown. The latter combination seemed to give slightly better 
results. 
Conditions of Growth. 
In southern Indiana Blasia frequents the banks of muddy streams, often 
growing on quite high elevations, where it is exposed in the summer 
months to considerable desiccation. Its habitat is one of fairly constant, 
though frequently, in times of drought, of rather scant moisture. Mitotic 
figures were not found to be plentiful, but practically all stages in the 
development of the spermogenous tissue with the exception of the spindle 
of the last division were observed. There seems to have been acquired 
here, as also suggested in the case of Porella , a correlation between the 
conditions of growth and cytological phenomena in the plant’s ability to dry 
up to a certain extent for a period of time, and then revive with rapid cell- 
division. Blasia , however, requires a much more constant supply of moisture 
than do the leafy Liverworts, but not so much as do the Marchantiales. In 
the latter, cell-divisions follow each other rapidly, and the spermogenous 
tissues are, as a rule, brought to maturity without long periods of delay. 
There is a noticeable difference between the cells of actively dividing 
spermogenous tissue and those which apparently have been some time in 
a resting condition. Fig. 1, PI. XI, represents a stage in which many 
antheridia are found. The nucleus shows a very faint membrane, enclosing 
the nucleolus surrounded by a substance very fine and evenly granular. The 
cytoplasm surrounding the nucleus has very much the same appearance, 
except that it is somewhat more coarsely granular. In some cells the 
structures appear to be more or less disorganized and stain very poorly, 
while others show definite organization. It is important to consider this 
