Medical Apparatuses 437 



according to him, by the fact that a toothache disappeared in 

 compressed air. However, observations on the conjunctiva and 

 the ears of rabbits showed nothing definite; besides, he says, there 

 are too many causes of complications. But what is the immediate 

 cause of these modifications in the circulatory acts? 



The decrease of the pulse and of the tension must be due to an 

 effect on the heart action. Is this effect the result of respiratory- 

 changes? Does it depend on the pressure exerted on the muscles and 

 the ganglia of the heart? Or on some other circumstance? I do not 

 venture to give an authoritative opinion. 



The work of G. von Liebig 1G contains the account of the experi- 

 ments made at Reichenhall in the apparatuses of the Mack brothers. 

 The average pressure at Reichenhall is 72 to 73 centimeters; in the 

 apparatuses it varied from 100 to 130 centimeters. 



G. Liebig first observed, as did so many others, that respiration 

 slackened in compressed air. In Kramer, one of the persons whom 

 he observed, it fell from 10 to 7 per minute, and remained at this 

 figure under normal pressure: but in the other, Mack, one of the 

 proprietors of the establishment, who was accustomed to com- 

 pressed air, the difference was only from 4.3 to 4.1. 



The respiratory amplitude was also modified in the first subject. 

 It rose from 0.819 liters to 1.073 liters, and remained at 1.068 liters. 

 But in the second, the change was only from 1.437 liters to 1.489 

 liters and we may consider it as non-existent. 



Mayer ,7 made similar observations on a lady affected with 

 dropsy and on himself: 



He noted the usual phenomena. But (contrary to Vivenot) he 

 found a constant slackening of the pulse, which he explains by in- 

 creased circulatory resistances (increased pressure on the heart and 

 the vessels); the respiration was also slowed down. The vital capacity 

 of the lungs increased in a perceptible manner which seemed to be 

 persistent. The increased combustion raised the temperature in the 

 patient from 37.3° to 37.7°. 



The work of Marc 18 is more interesting, although it deals only 

 with an observation which Dr. Stachelhausen, who had been suf- 

 fering from hemoptysis and emphysematous asthma for four years, 

 made upon himself. 



After treatment for a month, a considerable improvement was 

 made; but I have no intention of dwelling on pathological details. 

 The most striking detail of the observation is the marked change 

 caused in the number of heart beats and of respiratory movements; 

 I have summarized the author's figures in the following table: 



