148 Biochemical Proceedings, Hygienic Congress [Sept. 



whenever the first Symptoms appear, is by far the most efficient treat- 

 ment, as both experiment and the experience of engineers testify. 



On account of the heat and the high relative humidity of com- 

 pressed air, the worker in a caisson is under conditions which tend to 

 lower his efficiency. Not only this, but his appetite is likely to suf- 

 fer and his general condition after some time to deteriorate so that 

 he becomes liable to infections if not to caisson disease itself. The 

 Caissons should therefore be well ventilated and the wet bulb ther- 

 mometer kept as low as possible. Means for doing this were dis- 

 ciissed. In the choice of men for caisson work attention should be 

 paid to age, body weight and f atness and while engaged in the work 

 the men should be kept in good training. 



Certain aspects of the influenae of muscular exercise upon the 



respiratory System 



THEODORE HOUGH 



Muscular activity increases the respiratory exchange from three- 

 to tenfold, thus making demands on the System comparable only 

 with those of the more severe forms of dyspnea. In meeting the 

 respiratory needs of the tissues there are secondary effects of hy- 

 gienic importance, such as the increased aspiration of the thora'x 

 upon the return of venous blood to the heart and also upon the flow 

 of lymph in the larger lymphatics ; this increased lymph flow is feit 

 in the interstitial Spaces of every organ in the body, thus favorably 

 influencing the environment of every cell. 



The introduction with more vigorous exercise of physiological 

 strain makes it important to inquire into the exact condition of the 

 organism revealed by the accompanying respiratory phenomena. 



Of the conditions known to increase the work of the respiratory 

 Center Geppert and Zuntz have excluded, as exciting causes of the in- 

 creased breathing movements of muscular activity, afferent Impulses 

 from the working muscles and deficiency of oxygen in the arterial 

 blood; their work also shows a decrease of the total {i. c, free and 

 combined) carbon dioxid of the arterial blood; it does not establish 

 a diminished tension of this gas in the respiratory center, and it is 

 possible (Haidane) that there may be increased tension of this gas in 



