452 RESEARCHES ON FUNGI 



(Figs. 229 and 230). Occasionally they arise within the tissues of 

 a leaf between the two layers of epidermis. They are orange-yellow 

 or brown in colour, 2-15 mm. broad, and mostly somewhat flattened. 

 In continuously rainy weather sclerotia may be formed on the 

 berries and more rarely on the under side of leaves, even before 

 these organs fall to the ground. 



The sclerotia, as observed by both Kuyper and Stahel, never 

 give rise to any sporophores. In moist surroundings, e.g. under 

 trees and in cultures, they send out feathery branching mycelial 



Fig. 230. — Sclerotium cojjeicola. Germinating sclerotia on green leaves of 

 Coffea liberica. The mycelial strands have produced numerous appres- 

 soria. Photographed by G. Stahel. Reduced to three-quarters of the 

 natural size. 



strands which grow over the surface of the dead leaves and fruits 

 to which they are attached (Fig. 230). These mycelial strands, 

 which Stahel refers to as rhizomorphs, under favourable weather 

 conditions form gemmifers, the gemmae of which may be carried 

 away by the wind and deposited on leaves and fruits, where they 

 may form disease spots and thus reproduce the species. Some 

 sclerotia, out in the open, were found by Stahel to have retained 

 their vitality for one and one-third years. The sclerotia of Sclerotium 

 cojfeicola are thus well fitted for carrying the fungus over periods 

 of drought and other adverse weather conditions. 



In my laboratory at Winnipeg, a malt- agar plate was inoculated 

 with the mycelium of Sclerotium cojfeicola. The mycelium spread 

 radially over the agar and, in the course of two or three weeks, 



