RESPIRATION 



291 



animal such as a man, and roughly speaking is proportional to 

 the ratio of external surface to body weight. As was shown by 

 Dr. Florence Buchanan,^^ the pulse rate and respiration rate vary 

 in about the same proportion. Thus in a canary the pulse rate, as 

 recorded photographically by means of the capillary electrometer, 

 was about 1,000 per minute, the rate, as compared with that in 

 man, being greater in proportion to the more rapid metabolism. 

 The circulation rate in a small animal is thus enormously greater 

 than in a large animal, and indeed must be so ; but the proportions 



I 



I 



I, 



400 600 /ZOO /6pO 2000 2400 Z80O 



Wei^ of Rabbiis in Grammes 



3200 



Figure 71. 

 Blood volumes of rabbits in cc. of blood per 100 grains of body weight. 

 The curve shows what the blood volumes would be if they varied in the pro- 

 portion of body surface to body weight. The dots and crosses show average 

 results of actual determinations by the modified Welcker method. Dots repre- 

 sent results of Boycott : crosses of Dreyer and Ray. The numbers indicate 

 number of determinations for each group of observations. 



between the different parts of animals, including the blood, do 

 not depend on differences in size of the animals. From a very 

 limited number of experiments on animals, Professor Dreyer of 

 Oxford^^ drew the extremely improbable conclusion that in ani- 



*' Buchanan, Science Progress, July. 1910. 



"Dreyer and Ray, Philos. Trans. Royal Society, B, CCI, p. 138, 19 10; also 

 Dreyer, Ray, and Walker, Skand. Arch. f. Physiol., 28, p. 299, 191 3' 



