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W. J. CROZIER 



Then cooled down slowly (for 19 minutes) to 20.0°; pulsations (slowly revived) 

 required 150 seconds for 10 movements (the usual rate 60 minutes after amputa- 

 tion being 60 to 75 seconds for 10 pulsations) . All movements ceased in about 

 10 minutes more. 



These experiments were checked by many others of similar 

 type which gave essentially the same result. 



The main object of these tests being to ascertain the magni- 

 tude of complications possibly introduced into the experiments 

 by temperature effects, there is given in figure 23 some of the 

 curves derived from different tests under several of the possible 

 conditions of temperature change, and in f gure 24 are collected 

 the data from all the temperature experiments with isolated 

 cloacae. 



The discussion of these results with regard to the significance 

 of the temperature coefficient would be unprofitable," since (in 

 view of the source of complication above noted) decisive evidence 

 could be obtained only by the study of isothermal exhaustion 

 curves. But it may be pointed out that the hysteresis effect to 

 which attention has been called indicates that some physical 

 alteration of the substance of the pulsating tissues has occurred 

 at the temperatures which produce this hysteresis effect. It is 

 difficult to believe that this influence is discontinuous, and, as 

 Adrian ('14) has most recently pointed out, the van't Hoff equa- 

 tion holds only in homogeneous systems in which no alteration 

 of the components is induced by temperature changes. In other 

 words, there is a time-factor to be considered when working with 

 temperatures removed from the normal. It is the neglect of this 



" Putter ('14) has recently given an exhaustive treatment of the temperature- 

 variability curve from the standpoint of the linked reactions occurring in living 

 systems. 



