476 Historical 



manent slackening of the respiratory movements. So then he 

 resorts to another kind of explanation: 



I can explain this fact (he says) only by the unquestionable 

 increase in the strength of the respiratory muscles, which can alone 

 account also for the increase of the vital capacity of the lungs notice- 

 able even at the first treatment. 



Here he relies upon the conclusions of a memoir by J. Lange, 28 

 which I could not procure: 



Dr. J. L., in his work on the physiological and therapeutic effects 

 of compressed air, concluded from a series of experiments, the accu- 

 racy of which I can vouch for, that in it the negative pressure increased 

 considerably during the inspiration, and the positive pressure during 

 the expiration. If then the respiratory muscles gain strength, we are 

 justified in assuming that all the rest of the muscular apparatus shares 

 in this increase of strength. This Dr. J. L. proved by a series of 

 experiments, and he established it as a fact that if patients have been 

 subjected to the effect of compressed air for some disease of the lungs, 

 they feel their strength increasing after a few treatments, and muscu- 

 lar exercise becomes easier and less tiresome for them from day to 

 day. 



The same author says also: It is difficult, if not impossible, to 

 measure this increase in strength. Experiments do not give us results 

 of absolute quantity. They show us, however, that an increase in 

 power of the whole muscular system is produced, and that it is fairly 

 large .... 



The increase of muscular strength in compressed air may be con- 

 sidered a proof of the absorption of a greater quantity of oxygen. 

 This absorption is carried on especially by the lungs, but partly also 

 by the skin. Sandahl justly states that the skin has a respiratory 

 power and that under the influence of a strong pressure, which pro- 

 motes endosmosis, it would absorb more oxygen. (P. 27.) 



G. Lange comes next to the slackening of the circulation, and 

 quotes the explanation of Vivenot: 



Could one not somehow explain (he says) the slackening of the 

 pulse by the fact that the pressure exerted over so large a part of the 

 capillary system and the small arteries makes the passage of the blood 

 there more difficult? 



The presence of free gases in the blood makes a compression 

 possible, and the vessels, especially those which are situated on the 

 surface, contract so much that sometimes even slight hyperemias dis- 

 appear rapidly. 



The observations relating to the effect of the compressed air on 

 the functions of the nervous system are interesting enough to be 

 quoted in full; we find again in their explanation the idea already 

 suggested by different authors, and particularly by M. Junod 



