Germination of Tcleutospores of Ustilaginco'. 7 7 



part of their length ; or the end of one may become united 

 with the central segment of another, and so forth (Fig. 5). 

 These various fusions take place only in spores grown in 

 water. Brefeld has shown, however, that when cultivated 

 in a medium which is capable of supplying suitable nutri- 

 ment to the spores, these various fusions do not take place. 

 He discovered that an aqueous extract of the excreta of 

 herbivorous animals, sterilized by discontinuous boiling, 

 afforded such a medium {iidhrldsiing). Spores of U. sege- 

 tujii placed in Brefeld's nutrient fluid germinate sooner 

 than in water. Not only so, but the promycelia and the 

 promycelial spores are larger than those produced in water. 

 No fusion of spores or buckling of promycelia occur. The 

 most remarkable fact is that the promycelial spores mul- 

 tiply themselves by budding, very much after the manner 

 in which yeast-cells multiply themselves in saccharine fluids 

 (Plate VII. Figs. 8-10). Brefeld has kept them thus repro- 

 ducing themselves for more than a year, by replacing the 

 nutrient fluid as it became exhausted. The promycelial 

 spores continue to reproduce themselves by budding, as 

 long as the nutrient fluid remains unexhausted ; when this 

 occurs they cease to bud, and fuse in various ways, as is 

 seen when germination takes place in water. The yeast- 

 spores of this species produced in his nutrient fluid arc 

 rather larger than the primary spores produced from the 

 promycelium in water ; they are, however, of the same 

 shape, and measure from 9 to 30/i in length, and from 

 3 to 5ju in breadth.* Kept moist, they retain their vitality 

 for about two months, but if allowed to dry, none germi- 

 nated after the sixth week. The teleutospores, on the 

 contrary, if kept dry, retain their germinative faculties for 

 a very long period. Brefeld found that at the end of two 

 years they germinated as freely as when fresh ; other 



* Brefeld, /oc. cit., p. 13. 



