EXCHANGE OF COLD-BLOODED ANIMALS. 
701 
ordinary conditions is so small that it may be neglected. It is to 
be noted, however, that Colasanti and Finkler 1 always found small 
quantities of marsh gas and hydrogen in the respiration chamber 
in which well-fed guinea-pigs were placed ; these gases probably 
came from the alimentary canal, for they were not found in the case 
of guinea-pigs deprived of food. Zuntz 2 and Tacke found that three- 
quarters of the hydrogen and marsh gas formed in the alimentary 
canal of a rabbit were absorbed by the blood and discharged by the 
Lungs. 
The respiratory exchange of cold - blooded animals. — When 
compared with warm-blooded animals, the respiratory exchange of 
most cold-blooded animals is very small, a fact which explains the 
small production of heat observed in this class of animals. 3 Some 
of the earliest determinations were those made by Vauquelin, 4 
Spallanzani, 5 Newport, 6 Treviranus, 7 Edwards, 8 and Aliiller. 9 They 
showed that the quantity of oxygen consumed and of carbon dioxide 
produced was for equal weights of animals generally much less in cold- 
blooded than in warm - blooded animals, the most marked exception 
being in insects. Later researches have confirmed these general conclu- 
sions, and have shown the conditions, which chiefly affect the respiratory 
exchange in these animals. Of these conditions the most important is 
the external temperature, a rise in temperature causing an increase, a 
fall in temperature a decrease in the respiratory exchange. In the 
following table the results of various observers are expressed for 
1 kilo, weight of animal and 1 hour, in order that they may be 
comparable : — 
Animal. 
£x - 
3 ~ c 
|| 1 Sc| 'CO., 
- 2 5 x 3 •= 
9 3 
Remarks. 
3 
H 
Observer. 
PROTOZOA— 
Collozoum wi 1 
ClKLEXTERATA— 
1 'arma/i i na has- 
tata 
Cestus veneris 
•1113 
•0087 
•0037 
1-06 
1-10? 
•79? 
16" One determination. 
16' The determinations 
f CO, , 
of — = show va- 
2 
nations from '36 
to 2-16. 
16 CO, . , 
— *■ vanes from 
°2 '07 to 2-06. 
Vernon. 10 
x Arch.f. d. ges. Physiol., Bonn, 1877, Bd. xv. S. 603. 
2 Arch. f. Physiol., Leipzig, 1894, S. 354. See also this article, p. 729. 
3 Article "Animal Heat," this Text-book, vol. i. p. 792. 
4 Ann. de. chim., Paris, 1792, tome xii. p. 273. 
5 "Mem. sur la respiration," par Senebier, 1803, p. 184; Journ. f. Chem. Physik. 
v.. Min., Berlin, Bd. iii. S. 378. 
6 Phil. Trans., London, 1837, pt. ii. p. 253. 
1 Ztschr. f. Physiol., 1832, Bd. iv. S. 23. 
8 " De l'inflnence des agens physiques sur la vie," Paris, 1824. 
9 " Elements of Physiology," trans. Baly, 1838, vol. i. p. 310. 
10 Journ. Physiol., Cambridge and Loudon, 1895-96, vol. xix. p. 18. 
