768 Experiments 



The activity of organic combustions then increased at first, and 

 then diminished, after passing a certain maximum which is prob- 

 ably above 2 atmospheres. 



Cold-blooded animals gave me a similar result. But for them it 

 was not necessary to use such a complicated apparatus, considering 

 the low level of their respiration. The arrangement of the equip- 

 ment was the same as in the experiments made on tissues (Chapter 

 VI), represented in Figure 74; the animal was placed in the flask, 

 raised on a little tripod which prevented it from touching the pot- 

 ash solution. 



Experiment CCCXXVIII. January 11. Three frogs (A, B, C), nim- 

 ble and healthy, are placed each in one of these apparatuses. The 

 temperature is 15°. 



A weighs 28 gm. and is placed in ordinary air; 



B weighs 20 gm., air with 56.3% of oxygen; 



C weighs 20 gm.; air with 92.5% of oxygen. 



The animals are left in these conditions until January 15. 



We then made the analysis of the potash solutions and read the 

 graduated bells. The result was 



A consumed 205 cc. of oxygen and produced of CO=. 



B consumed 157 cc. of oxygen and produced 71.8 cc. of CO2. 



C consumed 114 cc. of oxygen and produced 62.8 cc. of C0 2 . 



If we take account of the different weights of these different 

 animals and if we reduce them all to 20 gm., we see, when we reduce 

 the oxygen content of the air to corresponding values in barometric 

 pressure, that there was: 



At 1 atmosphere, 146 cc. of oxygen consumed and of C0 2 pro- 

 duced. 



At 2.7 atmospheres, 157 cc. of oxygen consumed and 71.8 cc. of CO? 

 produced. 



At 4.4 atmospheres, 114 cc. of oxygen consumed and 62.8 cc. of CO: 

 produced. 



This experiment brings us to the same conclusions as the preced- 

 ing in regard to the intra-organic combustions. 



D. Pulmonary Capacity. 



The experiments which I reported some pages back corroborated 

 the statement of the earlier authors that the maximum inspiration 

 is greater in compressed air than at normal pressure. 



Since this modification is rather considerable and since it is the 

 instantaneous result of the increase of the ambient pressure, I was 

 led to believe that it is due to a mechanical action, acting, of course, 

 upon the only compressible part of our body, that is, the intestinal 

 gases. The mere diminution in volume of these gases should, in my 

 opinion, have as its result an increase of the thoracic cavity, since 



