CHEMISTRY OF DIGESTION AND NUTRITION. 301 



rise of outside temperature has naturally the opposite effect : oxygen-consump- 

 tion and CO 2 -elimination are diminished. This effect of temperature upon 

 the body-metabolism is due mainly to a reflex stimulation of the motor nerves 

 to the muscles. The temperature-nerves of the skin are affected by the rise 

 or fall in outside temperature, and bring about reflexly an increased or a dimin- 

 ished innervation of the muscles of the body. The fact that variations in 

 outside temperature affect only the consumption of non-proteid material falls 

 in, therefore, with the conception of the nature of the metabolism of muscle in 

 activity, given above. When the means of regulating the body-temperature 

 break down from too long an exposure to excessively low or excessively high 

 temperatures, the total body-metabolism, proteid as well as non-proteid, in- 

 creases with a rise in body-temperature and decreases with a fall in temperature. 

 In fevers arising from pathological causes it has been shown that there is also 

 an increased production of urea as well as of CO 2 . 



Effect of Starvation. A starving animal must live upon the material pres- 

 ent in its body. This material consists of the fat stored up, the circulating 

 and tissue proteid, and the glycogen. The latter, which is present in compara- 

 tively email quantities, is quickly used, disappearing more or less rapidly 

 according to the extent of muscular movements made, although in any case it 

 practically vanishes in a few days. Thereafter the animal lives on its own 

 proteid and fat, and if the starvation is continued to a fatal termination the 

 body becomes correspondingly emaciated. Examination of the several tissues 

 in animals starved to death has brought out some interesting facts. Voit took 

 two cats of nearly equal weight, fed them equally for ten days, and then killed 

 one to serve as a standard of comparison and starved the other for thirteen 

 days : the latter animal lost 1017 grams in weight, and the loss was divided as 

 follows among the different organs : 



Actual loss Loss to each 100 grams 



(in fresh organ). (fresh organ). 



Bone 55 grams. 14 grams. 



Muscle 429 " 31 " 



Liver 49 " 54 " 



Kidney 7 " 26 



Spleen 6 " 67 



Pancreas 1 " 17" 



Testis 1 " 40 " 



Lung 3 18 



Heart tf " 3 



Intestine 21 18 



Brain and cord 1 



Skin and hair 89 " 21 



Fat . 267 " 



Blood 37 " 27 



According to these results, the greatest absolute loss was in the muscles (429 

 grams), while the greatest percentage loss was in the fat (97 per cent.), which 

 had practically disappeared from the body. It is very significant that the 

 central nervous system and the heart, organs which we may suppose were in 

 continual activity, suffered no loss of weight: they had lived at the expense of 



