Ii8 
FRANK DUNN KERN 
fungi. Recent researches have shown that the old belief in the dis- 
appearance of sexuality in the parasitic fungi is no longer tenable. 
Harper has summed up the situation for the fungi in the statement 
that "the evidence is now generally accepted that either a typical 
conjugation of normally differentiated gametes and their nuclei or 
some form of substitute for it is everywhere present." The very fact, 
however, that there is here interpolated the phrase ''or some form of 
substitute for it" suggests strongly that although there may not be a 
disappearance of sexuality there may be a degeneration. In fact the 
author just quoted states further that the fungi exhibit some funda- 
mental modifications of the process of sexual fusion as found else- 
where. The question whether these variations are to be regarded as 
degenerations may be debatable but inasmuch as they are considered 
substitutions for sexual fusions that would appear to be implied. It 
should be noted here that while sexual reproduction can be shown not 
to be entirely impossible for certain forms yet its occurrence may be 
exceedingly rare. Long patient researches with some forms such as 
the late blight fungus of potatoes have led to an almost inevitable 
conclusion that there is not a disappearance of sexuality but that 
there is a loss of sexual vigor. It seems reasonable to conclude that 
the presence of both somatic and sexual modifications in parasites 
warrant the continued association of degeneration with parasitism. 
In connection with this view that parasitism is .a degenerate adap- 
tation it would be interesting to know whether there are any cases 
where the parasitic habit has been conquered and a return made to a 
normal independent existence. MacDougal in speaking of the higher 
plants says that it is usual to consider them "as passing down an in- 
clined plane of atrophies, which would ultimately lead to their ex- 
tinction, without reference to the abundance of development of the 
host forms." He has not in his investigations obtained the slightest 
hint which would indicate the possibility of a retracement by which a 
parasite might regain its standing as an independent. Nor is there 
any evidence from the bacteria or fungi to suggest that the parasitic 
habit when once established ever can be overcome. Some investi- 
gators hold the view that certain groups of obligate fungous parasites 
have made morphological advances of a sporophytic nature but this 
is questionable and even if true could not be taken as an indication of 
a possible step toward abandonment of parasitism. Some evidence 
which seems to point in this direction comes from the animal kingdom 
