544 



FETCH : 



In A the spores are quite dry and in semi-darkness ; in B 

 they are merely air-diy, but under the same conditions of 

 hght. Similarly, C is quite dry, wliile D is only air-dry. C 

 and D were placed in a window and were exposed to full sun- 

 light every morning in December- January, from 7 a.m. to 

 1 P.M. In February-March tlieeun goes off the window earher, 

 and the vessels were therefore put outside each morning 

 until 12 nooift The mornings were sunny throughout the 

 sixteen weeks for which C and D were exposed, except on 

 eleven occasions. The black bulb thermometer {iri vacuo) 

 exposed in the window by the side of C and D reached 50 • 5 

 at midday in January. 



• Samples were taken from each lot every seven days and 

 placed in sterilized flasks of sugar cane extract. The results 

 are given in the following table. The experiment was begun 

 on November 14, and the first samj)les taken on November 21. 

 The times given under A, B, C, D are those which elapsed 

 before the formation of a good covering of macroconidia, 

 not the time of germination, which is at least t^vo days 

 earlier : — 



