134 



Journal of Agricultural Research voi. xviit. no. 3 



rootlets are usually found covered with a white weft of the mycelium of 

 the causal fungus. If the soil is kept moist and the dead plant remains 

 untouched, the fungus will grow out on the surface of the soil in radiating 



Fig. I.— a, intracellular nature of Sderotium rolfsii hyphae in cantaloupe tissue; B and C, manner in 

 which the fungus pierces host cells; D, E, and F, method of budding and formation of new mycelial 

 growth; G, manner of growth of mycelium, forming strands; H, dissolved middle lamellae of host cells. 



fans around the foot of the dead plant (PL 6, A). With sweet potatoes 

 in the seed bed the fungus often attacks young sprouts as soon as growth 

 starts, in which case the mycelial strands work their way upward and 



