Medical Apparatuses 435 



kidneys, the greater quantity of urine. Those complex symptoms, in 

 which the outer cold also has some influence, act only within physi- 

 ological limits. 



42. That is why the compression of the air causes no serious dis- 

 turbance in the circulation of the blood, even when it is carried to 4% 

 atmospheres. 



43. The same thing cannot be said of the stage of decompression, 

 which, when.it is too sudden, causes annoying and even very danger- 

 ous disturbances in the distribution of the blood. 



44. The stay in compressed air is therefore less dangerous than 

 the return to open air, which causes congestions, hemorrhages, pains 

 and particularly disturbances of equilibrium of different sorts in the 

 circulatory system, which, by the development of gas in the blood, 

 may even cause a stoppage of the circulation and consequently a 

 sudden death. 



45. The means to be used in the case of these symptoms is a 

 rapid return to compressed air. (Zur Kenntniss, etc. P. 489-495.) 



The series of Vivenot's works attracted the attention of physi- 

 ologists and physicians to the interesting symptoms which he was 

 the first to note or which he described with more accuracy than 

 the preceding authors. The publications followed each other 

 rapidly. 



Freud 13 noted a considerable increase in his pulmonary capacity. 

 After 30 air treatments, it had risen from 3100 cc. to 3600 cc; this 

 increase still persisted 5V2 months later. There were only four 

 respirations per minute. 



Elsasser, 14 who did his research in the apparatus of Gmelin, at 

 Stuttgart, summarized the observations of his predecessors and 

 his own in regard to the respiratory rhythm in the following 

 statements: 



1. The total value of the respiratory movements in a given time 

 is diminished . . . . ; 2. The decrease affects partly the frequency, 

 and partly the amplitude of the movements; the more nearly the 

 frequency approaches the normal, the less deep the respirations are; 

 if they are very rare, they become deeper; 3. In very deep inspirations, 

 a greater quantity of air enters the lungs than at normal pressure. 

 (P. 26.) 



Moreover, his memoir seems to be only a sort of summary of 

 the former works of Vivenot. It is especially devoted to thera- 

 peutics. 



But in the front rank of the authors who, after Vivenot, con- 

 sidered these questions, we must mention Professor Panum. The 

 work of the Danish scientist is exclusively of a physiological 

 nature. 15 We shall give it an important place in the following 



