362 



vcm'tabli' and l)iill)i)iis plants. The niycoliiini is soptale. irregularly brauch- 

 in,!^, and rn'(iiu'ntiy very iniicli vaiiiolalcd. It ^Tdws fi'iim the cracks in 

 the root as a wliite felt, later givini; rise to large, hard, Mack sclerotia. 

 When first formed, thes^e are white, but later they change to brown, and 

 linally black. Mature sclerotia are white or dirty-white within, of densely 

 woven threads and with a black cellular outer coat. As in the case of 

 the Black Kot fungus, they are for the purpose of carrying the organi.sm 

 over ]ieriods unfavorable to growtli and for giving rise to the perfect 



Fig. "). Crow.i Rot of ginsL'ng sliowin'g largi", well tk'vc'lopt'd sclerotia. (After Whetzel.) 



stage. I'nder suitable moisture and temperature conditions, tliey send 

 out germ tubes directly, just as the Hlack Unl I'uimus. The perfect stagi^ 

 iias never been obtained by the writer in pure cullure. although during 

 tile jiast winter an elTort was made to do so. .V large numl)er of sclerotia, 

 giduii on various media, were placed out of doors in sterile sand, con- 

 tained in earthen jiots, and this si)ring one-half of them were brought into 

 the greenhouse. Some of (be jiots containing the sclerotia were kept very 



