

few forms. After the main principles nave been worked out 

 for these selected forms it may become largely a matter of 

 routine to compare a large number of organisr..t> with respect 

 to the principles previously worked out. The four fungi 

 here to be considered offered opportunities for intensive 

 study, and they also furnished valuable material for com- 

 parisons. 



As naturally follows from the general concept of con- 



( 7 ) 



ditional control of physiological processes w/ , the relation 

 of the process studied to any given condition or set of con- 

 ditions are themselves determined by the remaining conditions. 

 For example, if the temperature relations of a given organism 

 are to be dealt with they must necessarily be stated along 

 v/ith as definite a description as possible of the non-temper- 

 ature conditions that are supposed to be effective. To 

 state that the mycelial mat of a given fungus was observed to 

 enlarge more rapidly at one temperature than at another means 

 little unless it is ulso stated just what sort of medium was 

 employed in the test, just what w^s the length of the time 

 period, just what relation this time period had to tne begin- 

 ning of the test, just what the radiation conditions were, 

 etc. By altering the non- temperature conditions, the rela- 

 lation of a given process to different maintained temperatures 

 may be profoundly altered. To illustrate stil] more concrete- 



( 7 ) Verworn, Xax. Kausale unci jnale Weltanschanung. 

 Jena. 1912. 



