ASPHYXIA IN A LIMITED QUANTITY OF AIR. 745 



the fact that the blood of the animal is generally arterial in colour. 1 

 The fatal amount of carbon dioxide appears to be about 25 per cent. 



An Atmosphere containing an Excess of Oxygen and of Carbon Dioxide. 



In the cold-blooded animals a marked difference is observed ; death 

 in such experiments is generally due to an excess of carbon dioxide, and 

 the fatal percentage, about 16, is much lower than in the case of the 

 warm-blooded animals. 



Important differences have also been observed by Edwards 2 and 

 Paul Bert 3 in the duration of life, under water, of animals of different 

 species, and in animals of the same species, but of different ages and 

 exposed to various degrees of external temperature. See table on p. 746. 



The importance of these observations lies in the fact that they con- 

 firm many of the results obtained by experiments upon the respiratory 

 exchange of different animals. Thus an examination of the above tables 

 shows that the small animals die more quickly than the big animals, 

 and it has been proved that weight for weight they have a more rapid 

 metabolism. 4 Further, a marked difference is observed in hens and 

 ducks, for the latter can live under water three or four times as long as 

 the former. The explanation of this fact is, according to Paul Bert, 5 to 

 be found in the relatively greater quantity of blood in a duck. A 

 similar condition appears to obtain in the seal and whale, 6 which can 

 remain under water from fifteen to thirty minutes. 



The tables also show that new-born animals born helpless and blind 

 resist submersion for a much longer time than adults, a fact known and 

 studied by Harvey, 7 Haller, 8 Buffon, 9 and Legallois, 10 but the duration of 



Paris, 1824, pp. 629-632. 



1 Bernard, quoted from Paul Bert, loc. cit. p. 522. 



2 "De 1' influence des agens physiques sur la vie," 



3 Loc. cit., p. 534. 



4 This article, p. 720. See also "Animal Heat," this Text-book, vol. i. p. 852. 



5 Loc. cit., p. 550. 



15 Burdach, "Traite" de physiologic," trad, par Jourdan, tome vi. p. 122. 

 7 "De Generatione," Amst., 1651. 8 "Elementa physiologise," 1 



" Histoire naturelle de 1'homme." 

 10 "(Euvres de Legallois,'' Paris, 1824, tome i. p. 93. 



1761, p. 316. 



