744 
CHEMISTR Y OF RESPIRATION. 
Before an}- conclusions are drawn from the results given in the 
foregoing table, it will be advisable to consider the cause or causes of 
death in these cases of asphyxia. Do the animals die from a want of 
oxygen, or are they poisoned by the accumulation of carbon dioxide ? 
In order to answer this question, experiments have been made on the 
duration of life of animals confined in air containing an excess of 
oxygen, or an excess of both oxygen and carbon dioxide. Many 
observations have been made by various physiologists, but the most 
complete are those of Paul Bert. 1 The following table gives some of 
his results : — 
An Atmosphere containing an E.ccess of Oxygen. 
Animal. 
Tempera- 
ture of 
Volume of 
Gases. 
Percentage 
Composition of 
Gases before 
the Experiment. 
Duration of Life. 
Composition of 
Gases at the 
time of Death. 
0„. 
N. 
C0„. 
Og. 
Warm-Blooded — 
Cat, young, 250 
25° 
ISOOc.c. 
55*5 
44-5 
3 hrs. 25 min. 
31 
16 
grms. 
Rat, adult, 80 
1A~- 
500 „ 
77 
•J.", 
1 lir. 45 min. 
20 
50 
grms. 
Rat, 6 weeks old, 
25° 
5 5 a , . 
66 
34 
2 hrs. 
29-5 
26 
50 grms. 
Rat, 4 days old . 
22° 
120 ., 
81 
19 
18 brs. 30 min. 
28-5 
Babbit, young. 
22° 
1400 ,, 
71 
29 
More than 5 hrs. 
43-5 
11 
20u grms. 
Sparrow, young 
25° 
750 ,, 
76 
24 
More than 5 hrs. 
29 
Cold-blooded — 
Grass snake 
875 ,, 
77 
23 
8 days 
13-5 
61 
Grev lizard 
27°-29° 
570 „ 
7'.' 
21 
70 hrs. 
15-7 
Toad 
6 -7' 
400 ,, 
100 
7 days 
17 
SI 
Frogs 
6 -7 
too ., 
100 
9 days 
13-7 
8 
A consideration of the following results leads to the conclusion, held 
by Mayow 2 as early as L674, that a warm-blooded animal confined in a 
limited quantity of air dies from the want of oxygen, and this con- 
clusion is supported by the fact that its blood is markedly venous 
and contains little or no oxygen. The percentages of oxygen and of 
carbon dioxide in the air at the time of death are about 3 and 
15 respectively. On the other hand, when there is in the air an 
abnormal excess of oxygen, and at the same time a great augmenta- 
tion of carbon dioxide, the warm-blooded animal dies from poisoning 
with carbon dioxide, and here again the conclusion is strengthened by 
Martigny, Arch. gen. de ratd., Paris, 1827, tome xiv. p. 203; Snow. Edin. Med. 
Journ., 1846, vol. lxv. p. 49; Claude Bernard, "Lecons sur les effets des substances 
toxiques et medicamenteuses, " Paris. 1857; W. Muller, Ann. d. C'hcm. v. Pharm., 1858, 
Bd. cviii. S. 257 ; Valentin, Zt*chr. f. rat. Med., 1861, Bd. x. S. 33 : Beau. Arch. g,'n. de 
mtd., Paris, 1860, Ser. 5, tome xvi. p. 64 ; 1S64, Sir. 6, tome iii. p. 1 ; Paul Bert, 
"Lecons sur la physiol. comp. de la respiration," Paris, 1870, p. 510. 
1 "Lecons sur la physiol. comp. de la respiration," Paris, ls70, p. 518. 
2 " Tractatus quinque," Oxonii, 1674. See also this article, p. 741. 
