EFFECT OF MUSCULAR WORK AND TEMPERATURE. 937 



to cause shivering or muscular tension no increase in the excre- 

 tion of CO2 results. This fact suffices to explain, therefore, the 

 physiological value of shivering and muscular restlessness when 

 the outside temperature is low. 



The way in which external te mperatures affect the body metabolism may 

 be more complicated than would appear from the above explanation. One 

 authority t asserts that heat and cold acting reflexly through the cutaneous 

 nerves affect the thyroid gland and cause the secretion of two hormones. 

 One of these produced by external heat inhibits the body metabolism, the 

 other, produced by external cold, stimulates metabolism. 



The fact that variations in outside temperature affect only 

 the consumption of non-protein material falls in with the con- 

 ception of the nature of the metabolism of muscle in activity, 

 given above. When the means of regulating the body tempera- 

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

 excessively high temperatures, the total body metabolism, pro- 

 tein as well as non-protein, increases with a rise in body tempera- 

 ture and decreases with a fall in temperature. In fevers arising 

 from pathological causes it has been shown that there is an in- 

 creased excretion of nitrogen as well as of carbon dioxid. 



Effect of Starvation. — A starving animal must live upon the 

 material present in its body. This material consists of the fat 

 stored up, the circulating and tissue protein, and the glycogen. 

 The latter, which is present in comparatively small quantities, is 

 quickly used, disappearing more or less rapidly according to the 

 extent of muscular movements made. Thereafter the animal lives 

 on its own protein 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 for comparison and starved the other for thirteen 

 days; the latter animal lost 1017 gms. in weight, and the loss was 

 divided as follows among the different organs: 



L088 TO 



Supposed Weight Actual, Loss Each 100 Gms. 

 OF Organs Before of Organs of Fresh Organ 

 Starvation. in Gms. (Percentage Loss) 



Bone 393.4 54.7 13.9 



Muscle 140.S.4 429.4 30.5 



Liver 9L9 49.4 53.7 



Kidney 25.1 6.5 25.9 



Spleen 8.7 5.8 66.7 



Pancreas 6.5 1.1 17.0 



Testes 2.5 1.0 40.0 



Lungs 15.8 2.8 17.7 



Heart 11.5 0.3 2.6 



Intestines 118.0 20.9 18.0 



Brain and cord .... 40.7 1.3 3.2 



Skin and hair 432.8 89.3 20.6 



Fat 275.4 267.2 97.0 



Blood 138.5 37.3 27.0 



Remainder 136.0 50.0 36.8 



t Mansfeld and v. Pap, "Pfluger's Archiv.," 184, 281, 1920. 



