840 ANIMAL HEAT. 



haemoglobin. 1 He found in two experiments that 100 volumes of 

 blood absorbed respectively 20'2 and 18'5 volumes of oxygen, and 

 produced thereby 14'63 and 14"91 calories. Now, the combustion of the 

 oxygen with carbon would produce 97*65 calories, but, in the formation 

 of oxyhaemoglobin, only 14*8 calories were set free that is, only a 

 seventh of the heat of combustion would be set free in -the lungs, the 

 remaining six-sevenths in the tissues. M'Kendrick 2 and Bottomley 

 have also been able, with a thermo-electric arrangement, to detect the 

 heat produced by the union of haemoglobin with oxygen. 



The production of heat in muscle. It has already been shown 

 that during active muscular work the temperature of the body is slightly 

 raised, although the loss of heat is ^t the same time greatly increased. 

 The muscles must therefore be an important source of heat, and a 

 further consideration will show that they are the chief source. The 

 bulk of the body is chiefly composed of muscle ; thus, in a dog weighing 

 11,700 grms., the muscles weigh 5400 grms., and the bones 2400 grms. 

 (Bernard) ; 3 and even in a much less compact animal, a bat weighing 

 19-94 grms., the muscles weigh 6'378 grms. (Pembrey). 4 



The production of heat as one of the phenomena of contraction 

 in a single isolated muscle, and the relation of heat to work during a 

 single contraction and during tetanus, are considered elsewhere. Here 

 the muscles have to be examined as seats of heat production, not only 

 during contraction, but during apparent rest ; and, further, as regards 

 the part they play in the production and regulation of the warmth of 

 the body. 



The muscles, even when they have been removed from the body, are 

 the seat of an energetic combustion (Humboldt, 5 Liebig, 6 Du Bois 

 Keymond, Valentin, 7 Mat teucci 8 ). The following comparative experi- 

 ments were made by Paul Bert. 9 Different tissues were removed from 

 a dog just killed, and the absorption of oxygen and discharge of carbon 

 dioxide were determined during a period of twenty-four hours, at a 

 temperature varying from O c to 10 : 



100 grms. of muscle absorbed 50*8 c.c. of oxygen, and discharged 56'8 c.c. of carbonic acid. 



,, brain ,. 45'8 ,, ,, 42'8 



kidney 37 "0 ,, 15 '6 



spleen ,, 27'3 ,, ., 15'4 



testis ,, 18'3 ,, 27-5 



broken bone \ , 7 . 9 _- 



and marrow \ ' " 



Regnard 10 has shown that the respiratory exchange of isolated muscle rises 

 and falls with the external temperature ; at 10 the discharge of carbon dioxide 

 by 1 kilo, of muscle is 40 c.c. in one hour, at 25 it is 129 c.c., and at 35 it 

 amounts to 294 c.c., but above 40 the discharge decreases. 



1 See also Davy, "Researches,''' London, 1839, vol. ii. p. 168. 

 *Brit. Med. Journ., London, 1888, vol. ii. p. 338. 



3 " Lecons snr la chaleur animale," 1876, p. 140. 



4 Journ. Physiol., Cambridge and London, 1895-96, vol. xix. p. 485. 



5 " Versnche neber die gereizte Mnskel-und Nervenfaser," Berlin, 1797. 



6 Arch. f. Anat., Physiol. u. wissensch. Med., 1850, S. 393. 



7 Arch, f.physiol. ffeilJc., Stuttgart, 1855, Bd. xiv. S. 431. 



s Compt. rend. Acad. d. sc., Paris, 1856, tome xlii. p. 648; Ann. de chim. et phys.^ 

 Paris, 1856, tome xlvii. p. 129. 



9 " Le9ons sur la physiol. comparee de la respiration," 1870, p. 46. 

 10 "Recherches expe"rimen tales sur les combustions respiratoires," Paris, 1879, p. 23. 



