

an exposure period of d days, with the given medium and with 

 a certain maintained temperature is s, mm. per time period of h_ 

 hours. These thr.ee factors enter into the statement of the 

 time rate of every process. In the present case h is always 

 taken as 24 hours, or 1 day, and d is always stated in terms 

 of h, so that d_ becomes nn, n being the num'cer of days of the 

 exposure period. It is of course not supposed that the rate 

 remains constant throughout the exposure period ; the ralueB 

 are simply mean 24 hour rates for the given period- 



The following tabulation of values obtained from table 

 III for Pytheacytis, temperature 30° c, illustrates these 

 propositions in a concrete manner. 



Length of exposure 

 period (d) 



1 

 2 

 3 

 4 

 5 

 6 



Length cf observation 

 period or ti^e factor 

 of rate (h) 



1 



1 

 1 



1 

 1 

 1 



Mean ^ate of 

 diameter 



increase 

 (s) 



7.0 



7.5 

 7.6 



7.4 

 7.3 

 7.1 



52 



