BARTHOLOMEW: HYALOPSORA POLYPODII 199 
relic of an autoecious condition which prevailed in connection with 
a uninucleate mycelium that developed from a sporidial infection. 
As a result of the passing of the aecial stage to the conifers, only 
binucleate mycelial stages are now found in the ferns. From the 
persistence of the primitive spore form under the changed con- 
ditions, one may infer that the autoecious condition in the history 
of these rusts existed for a long period of time. While not germane 
to the question as to the spore forms of the fern rusts, it may not 
be amiss to carry the speculation a little further with the suggestion 
that the angiosperms upon their appearance became infected by 
_aeciospores from conifers, and that consequently the most primi- 
tive rusts of phanerogams bear their aecia upon coniferous hosts. 
UNIVERSITY OF WISCONSIN, 
MApDISON, WISCONSIN 
