264 FUNCTIONS OF NUTRITION. 



QUANTITIES OF HEAT AND OF CARBONIC ACID PRODUCED BY THE DOG IN ONE HOUR. 



Condition Carbonic acid in Proportion 



of the animal. grammes. Heat units. between the two. 



(Fasting .... 3.455 12.630 1 to 3.65 



Dog No. 1 j ln digestion . 5.013 18.875 1 to 3.76 



("Fasting .... 4.405 16.500 1 to 3.72 



Dog No. 2 | In digestion . . . 4.337 19.390 1 to 4.01 



(Fasting .... 3.154 16.880 1 to 5.35 



Dog No. 3 | In digegtion . . m 3.846 21.960 1 to 5.71 



Thus the proportion of carbonic acid formed to the heat produced is 

 different in the three animals when compared with each other in the 

 same condition ; and it also varies in each animal under the different 

 conditions of fasting and digestion. 



The same observer found that under the influence of a low tempera- 

 ture in a state of repose, the production of heat was never increased, 

 but was usually diminished ; while that of carbonic acid was generally 

 somewhat increased and never diminished. 



Local Production of Heat in the Organs and Tissues. Although 

 the body, as a whole, presents a general standard temperature, its heat 

 is produced in each separate organ and tissue by the local acts of nutri- 

 tion. This is shown by the fact that each organ has a special tempera- 

 ture of its own, which increases or diminishes according to its condi- 

 tion of activity or repose. A large quantity of heat is produced in 

 the substance of the muscles,. In the experiments of Becquerel and 

 Breschet, the temperature o' the brachialis muscle, in a man, during 

 repose was 36.5 ; but, after repeated and energetic flexion, it was from 

 37 to 37.5c Bernard,* by placing thermo-electric needles in the gas- 

 trocnemii muscles of a dog, after section of the spinal cord to prevent 

 voluntary movements, found the temperature of the muscles on the 

 two sides sensibly equal ; but on producing contraction by galvanizing 

 one sciatic nerve, the temperature of the muscle on that side was 

 increased 0.1 or 0.2, while the venous blood returning from it became 

 darker in hue. Since the muscles constitute so large a part of the 

 mass of the body, it is evident that continuous muscular exertion 

 must, after a time, produce a general elevation of temperature. In the 

 muscles, during contraction, the increase in warmth is accompanied by 

 greater consumption of oxygen, and consequently by a darker color of 

 their venous blood. 



Heat is also produced in the glandular organs when in active secre- 

 tion, as shown by the temperature of the blood entering and leaving 

 their tissue. Under these circumstances the venous blood coming from 

 the gland is warmer than the arterial blood with which it is supplied. 

 According to the observations of Bernard on the dog, while the sub- 

 maxillary gland is in repose, its circulation is slow, and its venous 

 blood scanty and dark-colored ; the oxygen of the blood being reduced, 



* Kevue Scientifique. Paris, 1871, No. 1, p. 1064. 



