958 
Journal of Agricultural Research 
Vol. XXVIII, No. 9 
Of these names Sclerotinia cinerea would be the correct one to apply to the 
American form, could it be shown to be identical with S. cinerea of Europe, if one 
believes it to be proper to choose the first-known name given to any form of the 
fungus, be it the ascogenous stage or a conidia-bearing stage, and properly pub¬ 
lished with an adequate description. If one believes that the first name applied 
to the ascogenous form and accompanied by an adequate description should be 
the one chosen, then S. fructicola would be the correct name both for the American 
form and the European form, again assuming their specific identity. If the Ameri¬ 
can fungus is considered specifically distinct from the European, then the cor¬ 
rect name is Sclerotinia fructicola } since, so far as known, it is the name first given 
to any stage of the fungus, the description is adequate, and it is also a name that 
should be acceptable to those who believe that the first name given the perfect 
stage should be chosen. 
The name Sclerotinia americana is untenable whether or not one considers the 
American form specifically indentical with the European. In the former case S. 
cinerea holds priority, while in the latter case S. americana is far antedated by 
S. fructicola. 
Though at first the writers were inclined to believe there was sufficient evidence 
to justify consideration of the American form as specifically distinct from the 
European, further study has indicated that the differences, mainly physiologi¬ 
cal, are not sufficient to be regarded as specific. It seems best to regard the 
American fungus as a form or rather as consisting of a number of forms or races 
of Sclerotinia cinerea , accepting as the correct specific name the one first applied 
to the conidial stage of the European fungus. 
Races or strains of the European form have been recognized and studied by 
Wormald (IS), Killian (5), and others; of the American form by Wormald (14) 
and by Ezekiel (4). The writers have grown strains of the American fungus in 
parallel cultures with the European S. cinerea and have found the same differences 
noted by Wormald. 
None of the American strains had quite the characteristically scalloped mar¬ 
gins which the European form has when grown in plate cultures, but some of 
them had scalloped margins not greatly different from those of the European 
form (PI. 1, A and B ). The conidia of the American strains produced germ 
tubes which did not branch until they had become considerably longer than 
those produced by conidia of the European form,the germ tubes of which showed 
much branching shortly after their emergence. On the other hand, the strains 
of American origin when grown on an extract of dried peaches and subjected to 
the oxidase test, in accordance with a method described by Wormald (18), gave 
results which are in all respects identical with those produced by S. cinerea 
from Europe. The strains of the American form show great differences in their 
growth on artificial culture media. Although most strains when grown on 
4 per cent potato agar produce an abundance of conidia, some strains produce 
conidia in abundance only for a short time. With these strains the production 
of conidia becomes less with each transfer, and finally only microconidia are 
formed. One strain obtained from a single ascospore has been grown by the 
senior writer for four years and now produces conidia even more profusely than 
at first. Moreover, it produces conidia on many media on which every other 
strain tried has produced none. The differences in growth on artificial culture 
media between a strain such as this and one which produces only microconidia 
are very striking (PI. 2, A and B). The former forms a thin web over the 
surface of the medium, most of which is covered with numerous grayish masses 
of conidia. The latter slowly develops a thick white mat, having a powdered 
appearance caused by the profuse production of microconidia. The growth sel¬ 
dom covers more than a small portion of the plate or tube slant, possibly because 
