TILLETIA TRITICI 259 



spores, there was not a single exception to this rule. We may 

 therefore conclude that desiccation, for however short a time, is 

 fatal to every basidiospore of Tilletia tritici. This conclusion is in 

 harmony with the finding of Appel and Riehm, 1 who state that 

 the basidiospores (their secondary conidia) are destroyed by drying. 



The basal end of a basidiospore can usually be distinguished 

 from the apical, either before or after germination, by the presence 

 of a minute highly refringent particle on the convex side of its cell- 

 wall at the place where the basidiospore broke away from its 

 sterigma (Fig. 130, A, p). 



When basidiospores germinate in a film of water which has con- 

 densed on a glass slide in a closed chamber, there is no external food 

 available and growth takes place at the expense of the substances 

 contained within the protoplasm of the spore. Each spore on 

 germinating puts out a single germ- tube, usually from its apical 

 end but sometimes from its basal end (Fig. 130, A, c-f). This germ- 

 tube is very slender and may grow without branching until it is 

 several times the length of the spore, the growth being accompanied 

 by protoplasmic migration toward the apex of the tube and by 

 the formation of septa, or the germ-tube may branch. Often the 

 original germ-tube, while still very short, may cease to grow, in 

 which case a new germ-tube arises from the other end of the spore 

 and draws all the protoplasm toward its apex, protoplasmic migra- 

 tion and septation taking place as before (Fig. 130, A, g). Other 

 variations in germination are shown in Fig. 130, A, h, i. The 

 germ-tubes usually exhaust themselves and cease to grow without 

 producing any new basidiospores. Only rarely and on relatively 

 short germ-tubes are basidiospores ever produced. Germination 

 of an essentially similar type takes place on the free surface of sterile 

 water contained in a sterile watch-glass ; but, under these conditions, 

 the germ-tubes are somewhat more coiled than they are in moisture 



films. 



When basidiospores germinate on malt-agar, oatmeal-agur , or 



1 O. Appel and E. Riehm, " Zur Frage der Uberwinterung des Steinbrandes 

 im Boden," Mitt. K. Biolog. Anst. Land- u. Forstw., 1914, Heft 15, p. 6. Cited 

 from Woolman and Humphrey, Summary of Literature on Bunt or Stinking Smut 

 of Wheat, U.S. Department of Agric, Bull. No. 1210, 1924, p. 12. 



