720 CHEMISTR Y OF RESPIRA TION. 



was about 24 per cent, in the carbon dioxide, and 17 per cent, in the 

 oxygen. Sodium chloride and sodium bicarbonate had no effect on the 

 intestines or upon the respiratory exchange. Lowy suggests that the 

 therapeutic value of the waters at Carlsbad and Marienbad, in cases of 

 disordered metabolism, may be partly due to this stimulating effect of 

 sodium sulphate. 



The influence of the size of the animal upon the respiratory 

 exchange. 1 -The smaller an animal the greater is its surface in relation 

 to its mass, for the surface increases as the 'square, the mass as the cube. 

 Now, small mammals and birds' have a temperature equal to or even 

 higher than that of large animals of the same 'classes ; and, on account of 

 the relatively greater surface which they expose for the loss of heat, 

 they must have a relatively far greater production of heat than the 

 large animals, for there is generally no marked difference in the pro- 

 tective coat of fur or feathers. Heat is produced by a process of 

 combustion in the tissues, and the respiratory exchange is a measure, 

 although it may not be an absolutely exact one, of this combustion. 

 Theoretically, therefore, a much more vigorous respiratory exchange 

 should exist in the smaller warm-blooded animals. The experiments of 

 many observers, especially of Letellier, 2 Eegnault and Eeiset, 3 Pott, 4 and 

 Kichet, 5 have shown that such is the case, not only for animals of the 

 same species, living upon similar diet and having similar habits, but 

 also for animals of different species, with very different diets and 

 habits. 6 



Paul Bert 7 has shown that this difference in the rate of metabolism 

 in small and large animals has become habitual, for it persists even 

 when the animals are put under abnormal conditions of such a kind 

 that the loss of heat is relatively the same ; in such an experiment a 

 pigeon absorbed 234 c.c. of oxygen per 100 grms. of its body weight, and 

 a sparrow 467 c.c. of oxygen. 



A series of experiments have been made by Eichet 8 upon thirty-eight 

 dogs of different sizes, their weights ranging from 2 '2 to 28 kilos., and 

 the results show that the output of carbon dioxide bears a very constant 

 relation to the surface of the body, 0'0027 grins, per hour for each 

 .square centimetre of surface. A similar relation holds good for the 

 intake of oxygen, the respiratory quotient being 0'748. This difference 

 in metabolism is controlled by the nervous system, for it was found, 

 in eighteen dogs of different sizes, ansesthetised with chloral, that the re- 

 spiratory exchange was proportional to the weight of the body, 0*640 to 

 0*694 grms. C0 2 per kilo, and hour. A somewhat similar series of 

 observations, made upon birds 9 of different sizes and species, gave 

 similar results. 



1 For a discussion of this subject, see paper by Hoesslin, Arch. f. Physiol., Leipzig, 

 1888, S. 323, where numerous references are given ; Rubner, Ztsclir. f. BioL, Munchen, 

 1883, Bd. xix. S. 535. 



2 Ann. de chim. etphys., Paris, 1845, Ser. 3, tome xiii. p. 478. 



3 Ibid., Paris, 1849, Ser. 3, tome xxvi. p. 299. 



4 Landwirthsch. Versudisstat. , Bd. xviii. S. 81. 



5 Arch, de physiol. norm, et path., Paris, 1890, tome xxii. pp. 17, 490; 1891, tome 

 xxiii. p. 74. 



6 See tables, pp. 706-708. 



7 "Le9ons sur la physiol. comp. de la respiration," Paris, 1870, p. 503. 



8 Compt. rend. Acad. d. sc., Paris, 1889, tome cix. p. 190 ; Arch, de physiol. norm, ct 

 path., Paris, 1890, tome xxii. p. 17. 



9 Arch, de physiol. norm, et path., Paris, 1890, tome xxii. p. 490. 



