[Vol. 2 



450 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



ham, '97) must also remain, for the present, uncertain. It is 

 possible that Shaw's fungus is one of the Ascomycetes, at 

 least this is suggested by the figures of the sclerotia. 



In my opinion Shaw has correctly referred to Corticiuw 

 vagum B. & C. (accordingly to Rhizoctonia Solani Kiihn, 

 representing the vegetative phases of that species) another 

 fungus which he also found in India on the groundnut and 

 cowpea. Both the mycelium and the sclerotia of this second 

 organism as described by him agree with R. Solani as we 

 know it on carnation, beet, bean, lettuce, potato, etc., in 

 America and elsewhere, as far as reported. The descriptions 

 and measurements of basidia and spores are also in sufficient 

 accord. 



Shaw has even suggested that Rhizoctonia violacea Tul. is 

 the vegetative stage of Corticium vagum B. & C. No such 

 unfortunate confusion could result, however, had he been able 

 to study that which is accepted as Kiihn's organism on the 



potato together with the violet root felt fungus of Europe on 

 any of its hosts. He has obviously failed to find material of 

 the last named fungus in his studies thus far. 



Between Rhizoctonia Crocorum and R. Solani in the vege- 

 tative condition some of the important and easily observed 

 contrasting features as usually found are presented in the 



following table : 



Rhizoctonia Crocorum 



Rhizoctonia Solani 



An external felt, or mantle, of External mycelium, if notice- 



investing hyphae, confined 

 almost exclusively to under- 

 ground organs. 



able, only a web, or some- 

 times with flaky tufts, the 

 formation of a "collar" oc- 

 curring only at the time of 

 fruiting. 



Color of mycelial felt pink-red Color of web, if evident, dirty 



yellow to yellow-brown. 



Youn<2; 



or violet to violet-brown 

 with age. 



Protoplasm of young hyphal 

 cells soon develops a violet 

 reddish pigment. 



Infection cushions conspicu- Nothing comparable to infec- 



hyphal cells hyaline, 

 and even when llavous later, 

 pigment confined to walls. 



ous in the root-mvestmg 

 mycelium on most hosts. 



tion cushions, though on 

 potato sclorotia may serve 

 as points of infection. 



