54 AMERICAN Fern JOURNAL 
localities in Ohio, out of five hundred and one plants 
of these two species observed and plotted, nineteen 
only were B. dissectum, a ratio of about twenty-five to 
one. Has any reader ever found dissectum growing 
in groups by itself, or in greater numbers than obliquum 
when in the same group? It will not do to walk through 
a wood and report one dissectum seen and no obliquum. 
Only by painstaking search, yard by yard, if necessary, 
can the matter of occurrence and distribution be really 
settled. , 
The sporangia of dissectum are reported as smaller 
than those of obliquum, with numerous aborted spor- 
angia in addition. Microscopic study showed that 
even the apparently normal ones were often without 
any spores inside, or with small abnormal looking 
spores. If dissectum is really sterile, or nearly so this 
would account for its relative infrequency in comparison 
with obliquum. But if it is sterile what is the source 
of the plants which do occur? 
