AND ITS EFFECTS UPON ANIMAL LIFE. ] 9 



half. The jars were a little larger than those used in tlie experiments reported in 

 Table I. The proportion of oxygen present at the death of the animal was between 

 3 and 4 per cent., or lower than in the cases reported in Table I, while the car- 

 bonic acid had inci-eased to only about 7 per cent, instead of 12 per cent., as in 

 Table I. The smaller proporticni of cai-bonic acid here pi-eseut seems to have 

 allowed a gi-eater reduction in the proportion of the oxygen. Tliese results cor- 

 respond with those obtained with mixtures of gases by Taul liert (7, page 518), 

 who concluded that cai'bonic acid when inhaled is really a })oison, and with the 

 results of the elaborate researches of Friedliinder and llerter (44), which lead to 

 the same conclusion. 



In this connection the observations of Richardson (s) ;ire of interest. His 

 experiments were made chiefly with mice placed in jars having a capacity of 635 c. c. 

 In such a jar containing ordinary atmospheric air at 12.8" C, a mouse weighing 

 18.8 gi'ams became comatose in 1|- hours, which is, he says, the average duration of 

 life under such conditions. At a temperature of 6.6*^ C, the animal dies in forty 

 minutes. In an atmosphere of pure oxygen, at 6.6° C, the animal will live only 

 two-thirds as long as in atmospheric air, while at a temperature of 21^^ C. it will 

 remain conscious for three hours and lives twelve houi's, and at 10" C it remains 

 conscious for two hours and lives thi'ee or four hours. With atmospheric aii', 

 the modifications, he says, are less distinctly marked. 



The results of similar experiments made with air, and with different mixtures 

 of gases, at diffeient temperatures, are given in Table J in the Appendix. These 

 results show that the dui'ation of life, in confined places, is influenced to a very 

 marked degree by temperature, and that this influence is independent of the rich- 

 ness of the air in ox^-gen. Experiments Nos. 3 and 17 noted in Table J indicate 

 that an atmosphere consisting of 90 per cent, of oxygen and 10 per cent, of nitrogen 

 does not support life quite as long as does ordinary atmospheric air when the tem- 

 perature is 0° C, while at a temperatui'e of 50° C. the atmosphere I'ich in oxygen 

 su^ipoi'ts life much longer than the ordinary atmosphere, as is shown by experiments 

 Nos. 5 and 15 in the table. The gradual lise in temperature which must have 

 taken place in the ex[)eriments previously referred to, was probably but a small 

 factor in the i-esults obtained, because, as shown in the tables for those experiments, 

 the dui'ation of life and the proportion of oxygen present at death bear a constant 

 relation to each other. This they fail to do in the " Richardson " experiments. 



The tolei'ation which is acquired by an animal by prolonged sojourn in an 

 atmosphere which is gradually becoming richer in carbonic acid and poorer in 

 oxygen, makes it impossible to compare the results as to duration of life in such 

 experiments with the results of experiments in which the animal is placed at once 



