ological processes is an indication that more attention is 



now being given to this subject. There is still, however, 

 a great lack in our knowledge in this field especially as 

 regards plants. On certain animal processes somewhat more 

 work appears to have been done, though even in this field 

 much also remains to be accomplished. 



It should be remembered in this connection, also, 

 that the subject of the temperature responses in living 

 things involves more complicated problems than those just 

 suggested as having to do with maintained temperatures. 

 Most organisms (aside from warm blooded animals) are never 

 exposed, in nature, to maintained temperature for any con- 

 siderable period of time ; their temperature environment 

 is practically always in a state of flux. From this it 

 follows that a knowledge of the relation holding between 

 maintained temperatures and vital processes, no matter how 

 thorough such knowledge might be, cannot be expected to be 

 of immediate value in the interpretation of physiological 

 processes going on under natural conditions. Before any 

 great advance may be made in the study of temperature in- 

 fluences on such processes suitable methods will need to be 

 devised for dealing also with rate of temperature cnange as 

 an environment condition, aside from the degree of tempera- 

 ture itself. The experimental aspect of this phase of 

 physiological and ecological temperature relations remains 

 practically untouched a.s yet. It is almost unmentioned in 



the literature as a serious consideration, although MacEougai (1 ' 



(2) riacI'Ougal, D.T. , The a uxo thermal integration of climatic 

 complexes. Amer. Bot. 1 | 135-193, 1914. 



