

Since none of these fungi produces anything hut vege- 

 tative hyphae during the cultura oeriods employed, th< 



activities- being therefore not complicated by the formation 

 of any reproductive hcdies, these measurements of the mycelial 

 disks, and the daily increments of disk enlargement derived 

 from them, appear to furnish as satisfactory a cri teHon 

 physiological activity in general as might he found. The only 

 other criterion for such comparisons as these, that has heen 



generally used by physiological workers, is the rate of pro- 

 duction of mycelium measured on the basis of dry weight, a 

 the employment of this criterion offers great practical dif- 

 ficulty when agar medium and short culture periods are used. 

 The diameter measurements were accompanied by simple visual 

 observations as to the general appearance of the mycelial" mat 

 (its shape if not circular, its texture, etc) and by micro- 

 scopic observations as to any peculairities in hyphal form 

 that might he evident. These observations were recorded, 

 along with the diameter measurements, for each culture at each 

 time of observation. 



At the tins cf observation, each chamher was opened 

 fcr a fraction of a minute, to remove just one group of cul- 

 tures, all alike. These dishes were immediately wrapped in 

 cotton batting, to exclude light and prevent very rapid tem- 

 perature changes* -tfach dish was removed from the wrapping 

 fc~ a minute or less while the usual observations were made 

 and was then returned to the wrapping. Afte* - all cultures 

 of the rroup had been observed the entire croup was replaced 

 in its temperature chamber and another group was taken out 

 fcr observation. The time required for the entire operations 



