iod consiaer*d in deriving the rate^ it is al7vaye necessary to 

 regard experimentally determined raoee as averages. Trus, in 

 the present study, all rates of enlargement are to "he consider- 

 ed as average or mean 24-nour rates, and such are the values 

 given in table III - VI. These mean 24-hour rates may of 



course be reduced to corresponding ra.zaa on the basis of any 

 other unit of time, by employing a simple coefficient. 

 Thus a mean 1-hour rate is obtained oy dividing the given 24- 

 hour rate by 24, a mean 2-day rate is ohtained by multiplying 

 the given 24-hour rate by 2, etc. Since only mean rates are 



considered -- and instantaneous rates cannot be dealt with ex- 

 perimentally -- it makes no difference what time unit is em- 

 ployed. Twenty-four hour rates of increase in the diameter 

 of the mycelial disks are dealt with throughout this paper. 

 It may be remarked that corresponding rates of radial increase 

 may of course be obtained by dividing each given value by 2. 

 As has been stated, the spatial unit employed for all these 

 rate values is the millimeter. 



Besides the time unit for which the mean rates are 

 calculated (2* nours or 1 day, in the present instance) the 

 characterization of any process also involves a quantitative 

 statement of the length of time during which the process is 

 considered as in operation i that is, the length of the ex- 

 posure period in such experiments as these. It is usually 

 convenient to employ the same time unit for this statement as 

 is employed in the rate unit itself, and this is done in the 

 present study. Thus any mean growth rate is characterized 

 by the combination of one spatial value and two time values , 

 we say that the mean rate of enlargement of a given funp-us for 



51 



