70 



MAINTENANCE RATIONS OF FARM ANIMALS. 



may even lead to congestion of the latter. The process is analogous 

 to the closing of the windows of a room as the weather grows colder. 



There is evidently a limit to this method of regulation. If the 

 windows are entirely closed nothing more can be effected in this 

 manner, and if the weather continues to grow colder the fire in the 

 room must be increased. So if the external demand for heat becomes 

 so great as to exceed the limits of adjustment in the body more fuel 

 material is katabolized — that is, more heat is produced. This was 

 first demonstrated by Carl Voit, who obtained the following results 

 for the excretion of carbon dioxid by a man at various temperatures : 



Influence of external temperature on metabolism of man — Carl Voit. 



Tempera- 

 ture. 



Carbon 

 dioxid. 



Urinary 

 nitrogen. 



Tempera- 

 ture. 



Carbon 

 dioxid. 



Urinary 

 nitrogen. 



° C. 



Grams. 



Grams. 



°C. 



Grams. 



Grams. 



4.4 



210.7 



4.23 



23.7 



164.8 



3.40 



6.5 



206.0 



4.05 



24.2 



166.5 



3. 34 



9.0 



192.0 



4.20 



26.7 



160.0 



3.97 



14.3 



155.1 



3.81 



30.0 



170.6 





16.2 



158.3 



4.00 









Later and more comprehensive experiments with animals hy Rubner have 

 given corresponding results. Thus with two guinea pigs the following figures 

 were obtained in 24-hour experiments : l 



Influence of external temperature on metabolism — Rubner. 



Mature animal. 



Young animal. 



Tempera- 

 ture of air. 



Tempera- 

 ture of 

 animal. 



CO 2 per 

 kilogram 

 and hour. 



Tempera- 

 ture of air. 



Tempera- 

 ture of 

 animal. 



C02 per 

 kilogram 

 and hour. 



°C. 

 



11.1 

 20.8 

 25.7 

 30.3 

 34.9 

 40.0 



°a 



37.0 

 37.2 

 37.4 

 37.0 

 37.7 

 38.2 

 39.5 



Grams. 

 2. 905 

 2. 151 

 1.766 

 1..540 

 1.317 

 1.273 

 1.454 



°C. 





 10 



20 

 30 



35 



°C. 

 38.7 

 38.6 

 38.6 

 38.7 

 39.2 



Grams. 

 4. 500 

 3.433 

 2. 283 

 1.778 

 2. 266 



A later experiment by Rubner 2 upon a dog, in which the heat production was 

 measured by a calorimeter, gave the following results : 





Heat pro- 



Tempera- 



duction 



ture of air. 



per 





kilogram. 



C. 



Calorics. 



7.6 



83.5 



15.0 



63. 



20.0 



53.5 



25.0 



54. 2 



30.0 



56.2 



1 Biologische Gesetze, p. 13. 



-Arehiv fur Hygiene, vol. 11, p. 285. 



