30° centigrade. 



21 



4 hour8 preliminary warming. 



The presentation-time after 4 hours' preliminary war- 

 ming at 30° C. is thus (rounded off to 10"): 2'10". 



This case is a very simple one, as none of the déter- 

 minations had to be repeated, because they were in har- 

 mony with each other from the beginning: with a shortening 

 of the stimulation-time the percentage of curved plants 

 decreased regularly. Mostly this was not the case after 

 one détermination and some or even ail déterminations 

 had to be repeated one or more times, till the average 

 values showed a regular decrease with decreasing stimu- 

 lation-time. Hence the columns „total number of plants 

 used" and „lotal number of plants curved" hâve been 

 added to ail tables. 



§ 5. Expérimental object. 



In ail m y experiments coleoptiles of Avena saliva only 

 served as expérimental objects. In my sélection I was 

 guided by the conviction, that it was most important to 



