The Influence of Increased Barometric Pressure on Man. 285 



sized vessels and compressing the nerve-cells. The convulsions were due 

 to oxygen poisoning, and the bubbles, being formed of oxygen, were 

 eventually absorbed by the tissues. These bubbles supplied the nerve-cells 

 with oxygen until the circulation became re-established, so that no lasting 

 paralysis resulted, as occurs with nitrogen bubbles. It seemed, therefore, 

 probable that, if an animal be kept in oxygen until symptoms of poisoning 

 are well marked and there is danger of death, then the tissues will be unable 

 to combine with the oxygen liberated on sudden decompression, and embolism 

 will result. We decided to settle this question by analyses in the peritoneal 

 cavity, blood-vessels, and subcutaneous tissues. 



The technic employed was that described in the paper of Hill and Ham (3), 

 the animal being cut open under a funnel filled with water and inverted over 

 a basin of water. Before being passed under the funnel, the gas is carefully 

 washed out of the fur, and pains are taken to avoid opening the digestive 

 tract or lungs. The results obtained on frogs were as follows : — 



(1) Frog exposed to +20 atmos. 2 during 1 hr. lOmins. Eapid decom- 

 pression. Composition of gas obtained from the body , — 



O2 80 per cent. 



.N2 20 „ 



{' 



(2) Large Dutch frog. +16 to 20 atmos. 2 during 35 mins. Eapid 

 decompression. 



fC0 2 2-2 per cent. 



\ O2 75-6 



Uj 2 22-2 



(3) Frog. +20 atmos. 2 during 33 mins. Eapid decompression. Dead 

 on removal. 



C C0 2 2*5 per cent. 



\ 2 62-0 



UsT 2 35-5 



The saturation time in frogs differs so much from that of the Mammalia 

 that no very direct conclusions could be drawn from these results, and we 

 therefore extended our observations to rats, the following experiments being 

 performed : — 



(1) Three rats were exposed to +70 lbs. 2 for one hour. Two were 

 convulsed in 35 minutes, and at the end of the experiment they were all 

 moribund. One, however, still breathed after decompression, which took 

 3 J seconds. Analysis of the peritoneal gas yielded : — - 



2 54*5 per cent. 



JST 2 45-5 



y 2 



{; 



