3 8o RESEARCHES ON FUNGI 



A spore-fall method of making pure cultures of Tilletia tritici and 

 other Tilletiaceae from basidiospores is described. By means of this 

 method extensive mycelial mats of T. tritici may be obtained on agar 

 media within three weeks of inoculation. 



The mycelium of Tilletia tritici, when growing on an agar medium, if 

 exposed to very dry air, continues to produce and discharge basidiospores 

 whilst the agar is drying up. 



Freshly-discharged basidiospores, which have not been allowed to 

 dry, germinate in a film of water or on a nutrient medium to the extent 

 of 100 per cent., and germination begins within about an hour of the 

 discharge of the basidiospores from their sterigmata. 



In falling through dry air, basidiospores dry up and in so doing lose 

 their sickle shape, double up, and become pyriform. Basidiospores 

 which have once dried up never germinate. 



In the course of three months, the mycelium of Tilletia tritici, grown 

 on agar, gave rise to a number of typically rounded and reticulated 

 chlamydospores . 



The fall of the basidiospores of Tilletia tritici was observed by the 

 beam-of-light method. 



The maximum vertical height of basidiospore-discharge was found to 

 be about 1-0 mm. and the maximum horizontal distance 1-4 mm. 

 Tilletia tritici discharges its basidiospores to a greater distance than 

 either the Hymenomycetes or the Uredineae. 



The spore-fall method was employed for inoculating germinating 

 wheat grains with the secondary basidiospores of Tilletia tritici and 

 T. laevis. A considerable proportion of the inoculated plants yielded 

 bunted heads at maturity. It was thus proved that secondary basidio- 

 spores by themselves may cause infection of the host-plants. 



The promycelium of Tilletia tritici is negatively hydrotropic, but it is 

 neither heliotropic nor geotropic. 



The phenomenon of the migration of the protoplasm and the formation 

 of septa in the promycelium of Tilletia tritici has been investigated. Each 

 new septum, when first formed, separates a highly vacuolated subterminal 

 cell from the terminal cell which is densely packed with protoplasm. The 

 subterminal cell, however, soon dies and collapses. 



Chapter III. — The history of our knowledge of Sphaerobolus has 

 been reviewed. Descriptions of S. stellatus, S. stellatus var. giganteus, 

 and S. iowensis, based on Miss Leva Walker's investigations, have been 

 given. S. iowensis, as determined by Miss Walker, has chambered glebae. 



Dry discharged glebal masses of Sphaerobolus stellatus may retain 

 their vitality for upwards of ten years. When placed in water, their 

 gemmae send out a profuse, radiating, clamp-bearing mycelium. 



The glebal mass of Sphaerobolus stellatus, at the time of its discharge, 

 consists of a thin brown adhesive outer wall and of a core made up of 

 (1) many cystidia (large rounded or oval cells), (2) tens of thousands of 



