THE INFLUENCE OF PHYSICAL FACTORS 



93 



itself are probably acted upon, and increased muscular activity is pro- 

 duced by increasing temperature except as we have seen in the cluster 

 of bees which in the aggregate reacts against the temperature some- 

 what after the fashion of a warm-blooded animal. 



When the influence of the temperature on the metabolic processes 

 themselves is to be studied the nervous influences must of course be 

 excluded and the experiments made under absolutely standard condi- 

 tions. Comparatively few experiments conform to this obvious re- 

 quirement. 



Experiments on man made by Loewy [1890], Johansson [1896], 

 Rubner and Lewaschew [1897] have shown that a low surrounding 

 temperature does not produce any increase in the metabolic processes 

 unless voluntary or involuntary muscular movements are brought 

 about, but the standard metabolism of man has not been measured 

 over any range of body temperatures. 



It has been found repeatedly both on man and on animals 

 (Rubner) that even a slight increase in body temperature over the 

 normal produces an increase in the standard metabolism. 



The influence of low temperatures upon warm-blooded animals in 

 which the muscles were put out of action in various ways has been 

 studied by Velten [1880], Pfliiger [1878], Zuntz and Rohrig [1871], 

 Krarup [1902], Krogh [1914, 3], and others. 



Velten found on a curarized rabbit the following figures for the 

 respiratory exchange in the order given (Table XV) : 



TABLE XV. 



It is obvious from the low results, obtained when the temperature 

 was again rising, that the lowest temperatures must have had some 

 harmful effect on the animal. 



Similar but shorter series of experiments have been made on cura- 

 rized rabbits by Pfliiger and by Zuntz and Rohrig. Krarup made 

 some experiments on rabbits after pithing. The animals were allowed 



