MICHIGAN ACADEMY OF SCIENCE. 



51 



All mea.surements in micromillimeters. 



Several German authors have advanced the view that Sclerotinia cinerea and 

 Sclerotinia fructigena are really one species and represent what would now be 

 called the fluctuating variations of the species. But Woronin (1900) showed 

 with cultures of the conidial stage only, that while the two species on artificial 

 cultures could vary the size of their conidia far beyond that found ordinarily 

 under natural conditions, so that those of Sclerotinia cinerea became larger 

 than those of Sclerotinia fructigena as usually found in the open, nevertheless 

 there were constant differences recognizable whether they were grown on 

 artificial redia or were inoculated into the same host. Hence he concluded 

 that the two species were well marked. This conclusion has been confirmed 

 more recently by Aderhold (see table above) who found the asci and asco- 

 spores of Sclerotinia cinerea considerably smaller that those of Sclerotinia 

 fructigena. Whether l^oth these species occur in this country has not been 

 demonstrated. I have seen no evidence of the two species in Michigan, 

 and Reade reports only one of the two in New York. There are two striking 

 differences between the American and European forms of Sclerotinia fructi- 



