1915] 



DUGGAR — RHIZOCTONIA CROCORUM AND R. SOLANI 405 



leaves little to be desired, and one cannot mistake the fact 

 that he was discussing the disease, later known to be due to 

 Rhizoctonia Crocorum. He does not describe the more minute 

 morphological features, but discusses the macroscopic appear- 

 ance of the mycelium and sclerotial stages with such com- 

 pleteness that no doubt remains concerning the identity of the 

 fungus. The illustration included would likewise confirm 

 the description. He regarded the sclerotium, ' ' tubercule, ' ' as 

 the fruit body of a fungus allied to the truffles, and to this 

 special form of body, assumed to bear the organs of repro- 

 duction, he gave the name ' ' tuberoides. ' ' He likewise deter- 

 mined that a similar fungus is the cause of a disease found 

 upon the roots of Sambucus Ebulus, Coronilla varia, Ononis 

 spinosa, Muscari sp., and perhaps other plants. 



It was more than fifty years later that Fougeroux de Bon- 

 daroy (1785), discussing primarily a disease of the saffron 

 known as "tacon" gives further notes on the "mort du 

 saf ran, ' ' recording the occurrence of this disease on asparagus 

 when following (in the same soil) diseased crocus. 



After a further considerable lapse of time De Candolle 

 (1815) made a careful study of the pathology of a similar 

 alfalfa (Medicago sativa) disease in the vicinity of Mont- 

 pellier, but known throughout France. This led to the estab- 

 lishment of the genus Rhizoctonia as noted later. It is neces- 

 sary to the pathological account to note here, however, that 

 he recognized two species, R. Crocorum DC, primarily in- 

 habiting the crocus, and R. Medicaginis DC, on the alfalfa 

 and other hosts. He did not follow the development of the 

 fungus on the saffron, where host characteristics render some- 

 what obscure the appearance of the fungus ; and so for a long 



time the continuous violet felt of mycelium was associated 

 primarily with R. Medicaginis. 



Among other diseases of the carrot and beets in Germany, 

 Kiihn ( '58) found typical rots of these root crops, accom- 

 panied in both cases by a red-violet mycelium with other 

 characteristics indicating the alfalfa organism. He identified 

 the fungus as R. Medicaginis and thus established the greater 

 inmortance of Rhizoctonia diseases, and srreatlv extended the 



