1914] THAXTER—ASCHERSONIA 311 
the moment, the great variability of the individual species as 
regards habit, size, and color, the usually insignificant differences 
in their spores as well as the absence of any information as to the 
nature of their true hosts, except in a very few cases, combining 
to make their systematic study a matter of great difficulty. It 
has seemed desirable, therefore, in the present connection to 
attempt no more than a brief preliminary note on the ascosporic 
stage of A. turbinata, a species which, although it is extremely 
variable in habit, size, and color, is in its typical form quite unmis- 
takable. 
Although the perithecial stromata of Aschersonia turbinata 
are less highly specialized than they are in some of the species, the 
perithecia are usually aggregated in more or less distinct pustules 
which, more frequently in this than in others, seem to arise after 
the pycnidial form has practically ceased its activities. Often, 
however, the whole stroma is perithecigerous, and no pycnidia 
precede or accompany them. In some cases these perithecial groups 
are very small, as in fig. 1, where less than a dozen have been pro- 
duced from an old stroma bearing two well developed pycnidial cups. 
In fig. 2 a smaller but similar cup is associated with a much more 
definitely developed perithecial pustule, and fig. 4 shows in section 
a similar condition. In fig. 3 almost all of the original stroma is 
perithecigerous, a small pycnidial cup being present at the side, 
while the perithecia are more scattered. The section of such a 
specimen (fig. 4) shows a continuous homogeneous stroma, com- 
posed in all parts of absolutely identical, closely and intricately 
interwoven, thick-walled, undifferentiated hyphae; so that, were 
it not otherwise evident, there can be no question that the peri- 
thecia observed are those of the Aschersonia, and not of some other 
‘ngus parasitic on its stroma. It may here be mentioned, how- 
ever, that several such parasites have been observed, although their 
characteristics are quite different. 
€ perithecial cavities, as shown in fig. 4 at right, are almost 
Completely imbedded in this stroma. They are bottle-shaped, 
with a relatively narrow and well defined neck, about 440X150 p, 
and are surrounded by a more dense, thin perithecial wall, the 
Substance of which is like the similar but broader layer which sur- 
