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THE TEMPERATURE RELATIONS OF GROWTH IN 

 CERTAIN PARASITIC F^IGI ^ 



Howard S. Fawcett 



INTRODUCTION 



It is commonly recognized that, of the many different 

 and varying conditions that affect life processes, temperature 

 is one of the most important. The range of temperature at 

 which certain important physiological processes may occur at 

 all is relatively narrow, and comparatively slight temperature 

 changes produce marked effects upon the velocity cf ctner pro- 

 cesses having more extended ranges. Although many biological 

 ..estigators recognized the great importance of this subject, 

 the more detailed study of the effects of maintained tempera- 

 tures on vital processes awaited the development of simple, 

 adequate and inexpensive methods of artificial temperature 

 control. In the earlier investigations on temperature ef- 

 fects upon organisms it was often impossible to maintain the 

 desired temperatures constant throughout sufficiently long 

 periods of time to get results that might be considered as 

 related to maintained temperatures. In recent years a rap- 

 idly increasing number of papers reporting investigations on 

 the effects of maintained temperatures upon different pnysi- 



(l ) Sotanical contributions from the Johns Hopkins 

 University iio. 



