854 Experiments 



These evidences of distress are no doubt due to the sudden ex- 

 pansion of all the gaseous reservoirs of the organism, and we can 

 see that they are especially important in birds, in which these 

 reservoirs extend through the whole body; but equilibrium is re- 

 established almost immediately in the latter, because of the com- 

 munication of the air sacs with the trachea and consequently with 

 the interior. Mammals, and especially the herbivores, are a little 

 swollen by the expansion of the intestines and the stomach, but 

 they quickly expel the gases which distress them. This is shown 

 by the following experiment: 



Experiment CCCCXCIV. June 9. Dog, just killed by electrical 

 stimulation of the heart. There is introduced into the rectum, by the 

 help of a little bladder which completely covers the anus, a glass 

 elbow tube, the end of which is immersed several millimeters in a 

 glass full of water. The animal is thus placed in one of the large 

 cylinders of Figure 27. Then decompression to 34 cm. is made as 

 rapidly as possible; during this time bubbles of gas quickly follow each 

 other escaping from the anal tube; however the abdominal wall is 

 evidently swelling. Air is admitted; the wall collapses; there is still 

 a considerable quantity of gas in the intestine. 



The same effect is produced, as has been known for a long time, 

 in fish provided with a swimming bladder opening into the esopha- 

 gus, like the carp. If the decompression is not made too quickly, 

 one can see bubbles of gas from the bladders escaping from their 

 mouths; then, when normal pressure is restored, they drop to the 

 bottom of the water, since their density has become too great. 

 Under these conditions they return with difficulty to the surface 

 to swallow air and thus fill their bladders again; to get definite 

 information on this direct absorption, which might be doubted, I 

 made the following experiment: 



Experiment CCCCXCV. June 1. A carp weighing a half-pound is 

 subjected, in the water, to a decompression of two-thirds of an atmos- 

 phere. It throws off a great quantity of air. The crystallizing dish in 

 which it is swimming is then placed under a bell containing a mixture 

 of air, oxygen, and hydrogen in proportions not fixed. 



June 3. The fish dies; its swimming bladder contains 11.4 cc. of 

 gas of the following composition per 100: hydrogen 33.3; oxygen 16.7; 

 nitrogen 50.0. 



Let me say in passing that carp, in the natural state, when com- 

 ing to the surface of the water to swallow air, do not admit it to the 

 bladder, and probably use it only to aerate their gills more thor- 

 oughly. For example: 



Experiment CCCCXCVI. June 5. Carp weighing 200 gm. The ves- 



