TILLETIA TRITICI 



231 



from drying too rapidly. The preparation was then watched for 

 several hours under the low power of the microscope (magnifica- 

 tion, 160). 



Subsequently, it was found better to employ Petri dishes instead 



Fig. 113. — The Syracuse watch-glass method for observing the dis- 

 charge of the secondary conidia (secondary basidiospores) of Tilletia 

 tritici. A, two watch-glasses, a covering b ; m, a mycelial mat at 

 the surface of the agar seven days after the sowing of the chlamydo- 

 spores. B, arrangement of apparatus while the discharge of 

 secondary conidia is being observed : the upper watch-glass has been 

 removed ; a sterile glass ring g covered by a sterile cover-glass c 

 has been placed around a mycelial mat ; /, a perforated sheet of 

 moistened filter paper ; 0, the low power of the microscope with 

 the arrow indicating the direction of observation. Natural size. 



of Syracuse watch-glasses, as with the former it was easier to keep 

 the cultures pure. 



Under the conditions just described, the development and dis- 

 charge of secondary conidia was observed in detail. 



Sterigmata are never developed in the culture medium but 

 always in the air above it (c/. Fig. 1 14, C). Each sterigma is a short 

 slender conical structure. As soon as it has attained its full length, 

 the rudiment of a secondary conidium begins to appear at its apex. 



