140 SEVENTEENTH REPORT. 



and Puccima sorghi. The teleutospores of the first two germiuate 

 immediately, while the last requires wintering. 



Cronartium comptoniae Arth. As the teleutospores are formed 

 in columns, it is difficult to express the germinations in per cent. 

 Putting it relatively, there was no germination at 10° C, a slight 

 germination at 18° C, a good germination at 25° C, and no 

 germination at 35° C. 



Cronartium Comandrae Peck. There was no germination at 10° 

 C, a fair gennination at 18° C, a good germination at 21° C, 

 and no germination at 30° C. 



Pucehiia sorghi SchAv. The method used in the germination of 

 the teleutospores of this rust was the same as that used by Klebahn.^^ 

 The experiment was carried on in the laboratory at a temperature 

 of about 20° C. Leaves bearing teleutospores were alternately wet 

 and dried by covering them with water for three days, the water 

 being changed each day, and then drying them for three days. This 

 process was repeated five times and then, after drying, the teleuto- 

 spores were placed in a moist chamber, where fair germination was 

 obtained with the formation of well developed basidia and sporidia. 

 The material used was obtained from plants in the greenhouse dur- 

 ing January and so had not been weathered at all. Similar material 

 w"as also placed in bags out of doors, along with material which was 

 collected from nearby fields in the fall. Neither of these gave any 

 germination whatsoever, although both had been subjected to dry- 

 ing and wetting out of doors. From such results, Klebahn draws 

 the conclusion that the winter cold is not a factor which promotes 

 germination but rather that it hinders the germination of teleuto- 

 spores. 



Botanical Laboratory, University of Michigan, 1015. 



10. Zeits. fiir PflanzenkranklU'iton 24 :1. 



