388 BOTANICAL GAZETTE [JUNE 
4. That in many cases Botrytis develops as a saprophyte on 
plants primarily affected by the other species and is mistaken 
for the true parasite on account of the similarity of the myce- 
lium. 
5. That these forms and species can be distinctly separated 
by means of pure cultures, and distinguished from one another 
by the form and manner of growth of the sclerotia. 
Nore.—No reference has thus far been made to the internal structure of 
the sclerotia. De Bary (Morph. and Physiol. p. 31) draws a distinction between 
the Botrytis and Sc/. Liertiana forms on the basis of structure, but the writer 
has not been able to establish this or make a unifurm distinction. zg. 39 
shows a section which might represent any of the forms. 
Thus it appears from the study of this disease that Sclerotinia 
Libertiana has no connection with the Botrytis form in question, 
although at first sight this appeared to be undoubtedly the case. 
Confusion has arisen from the similarity in the parasitic myce- 
lium of the two forms, their similar effect on the plant and their 
frequent simultaneous occurrence; coincidences most deceptive 
to superficial examination but easily explained on the ground of 
the close relationship between the two species. Too general 
conclusions should not be drawn from the case of this disease, 
however, without taking into consideration a number of very 
similar ones which have been described. The writer has been 
fortunate in obtaining material of a number of these diseases, aS 
well as additional information concerning some of them, and has 
spent considerable time in comparing them with the results 
obtained from the study of the lettuce disease. Careful inquiry 
shows at once that much has been taken for granted in many of 
these cases and conclusions drawn which were based more Of 
apparent probability and general appearances than actual proof. 
It must be conceded that in a number of cases which are 
mentioned hereafter the conclusion seems at first sight fully wat- 
ranted that Botrytis cinerea is a stage in the life history of Sclero- 
tinta Libertiana, so intimately are the two forms associated with 
one another and so similar are they in effect and many details of 
structure. But, as will presently appear, in every case which the 
