^fJA/ 



UA-NXJA-L OW CATTLE-FEEDIKO. 



means by wliicli tliese variations are effected. Ifc Las 

 been sliown by immeroiis observations on rabbits, guinea- 

 pigs, and cats that, in warm-blooded animals, exposure to 

 cold largely increases botli tlie consumption of oxygen and 

 tlie excretion of carbonic acid, tlms sliowing a greater 

 activity of tlie chemical processes in the body and pre- 

 sumably an increased production of heat, wliile warmth, on 

 the other hand, has the converse effect, diminishing the 

 amount of chemical change in the body. 



The following selection from the results obtained by 

 Theodor ^ in an extensive series of experiments on a cat 

 will serve to illustrate these facts. Each experiment lasted 

 six hours. 



Temperatiiro. 

 J>eg. OenC 



-5.5. 

 -3.0. 



+0.2. 

 +t5.0. 



Carbonic 



acid 



excreted. 



Gcxms. 



Oxygen 



taken up. 



G-rois. 



19.83 



17.48 



18.43 



18.36 



18.24 



19.95 



17,90 



14.82 



Temperatui-e. 

 Dog. Cent. 



+12.3. 

 +16.3. 

 +30.1. 

 + 39.6. 



Carbonic 



acid 

 cxcretod. 



Grins. 



17.63 

 15.73 

 14.34 

 13.12 



Oxygon 

 taken np. 



G-rms. 



17.71 

 14.74 

 12.78 

 10.87 



In some of these experiments considerable motion on 

 the part of the animal took place, which may have influ- 

 enced the result, and Yoit f therefore executed a series of 

 similar experiments on a man. The man weighed about 

 156 lbs., and, after having been exposed for some time to 

 the temperature whose effect was to be observed, passed 

 six hours in the respiration apparatus fasting and in com- 

 plete rest. In this time he excreted the following quanti- 

 ties of carbonic acid and nitrogen : 



* Zeit t Biologie, XIV., 51. 

 t Ibid., XIV., 57. 



