478 Historical 



it would undergo a suction from which would result a stronger cur- 

 rent and the presence in the canal of a greater quantity of lymph. 

 Whether or not this explanation is true, I think that the weakness and 

 emaciation caused by a disease of the respiratory organs should lessen 

 as the cure proceeds, and that when the respiration is better, the 

 appetite is improved. The emaciation at the beginning probably 

 results from the greater absorption of oxygen, and the effects of this 

 gas are no longer depressing when the appetite increases. (P. 31.) 



The opinions of Elsasser 2<J are evidently only a reflection of 

 those of Vivenot: 



The effect of compressed air depends upon two principal factors: 



1. The increased mechanical pressure (a) on the exterior surface of 

 the body, (b) on the respiratory cavities; 2. the greater quantity of 

 oxygen and nitrogen breathed in a given volume. 



The first factor shows its effect first on the gases contained in the 

 body, then on the blood capillaries of the skin and the mucous mem- 

 branes, the walls of which are flattened. The second will act upon the 

 respiratory exchanges and movements. (P. 9.) 



And farther on, developing these principles: 



The pressure of an atmosphere and a half results in a compression 

 of the tissues, a contraction of the diameter of the blood vessels; the 

 supply of blood in the skin is diminished; slight cases of conjunctivitis 

 are cured, blistered surfaces and the ears of white rabbits grow pale. 



Similar changes are noted in the respiratory mucous membranes; 

 they become more compact, thinner, less rich in liquids and blood 

 From this fact, cures of inflammation of the lungs, etc. result .... 



What is the result of this forcing back of the blood? Does it not 

 cause interior congestions? Experience shows that the heart is not 

 affected by it, but works more quietly; there is no cerebral congestion 

 . . . . ; but the increase of appetite, of urinary secretion, and of 

 strength seems to be consistent with a greater quantity of blood. 



The second factor, the greater quantity of oxygen, has been too 

 much neglected hitherto .... If, at normal pressure, a healthy man 

 breathes 16 times per minute, and absorbs each time 30 cubic inches 

 of air, he will have consumed 480 cubic inches in one minute. But 

 under the pressure of 1V2 atmospheres, these 480 cubic inches which 

 he needs become 320; if he still breathes 16 times, each inspiration will 

 include only 20 cubic inches; with 12 respirations, it will rise to 26.6 

 cubic inches; with 8, to 40 cubic inches .... If therefore the proportion 

 thus calculated is not observed, more oxygen will be introduced into 

 the lungs in a given time, which explains the statements of the 

 authors about the greater absorption of oxygen, the increased hema- 

 tosis, the stimulated organic combustion, etc. (P. 13-17.) 



Panum, 30 in the work which we have already quoted (pa^e 435) , 

 justly criticizes the method employed by Vivenot in measuring the 

 quantity of carbonic acid produced in a given time; 



