462 Historical 



and because this sort of rarefaction takes place in a confined air 

 mingled with harmful gases. 



In regard to the muscular pains, he rejects the explanation of 

 Pol and Watelle: 



Because we did not find that the blood absorbed a greater pro- 

 portion of oxygen than normally. (P. 112.) 



But we admit with Francois that the compression of the air forces 

 a certain quantity of air into the tissues. This fact is demonstrated by 

 the cases of subcutaneous emphysema. (P. 114.) 



As to the serious symptoms, they are, in the opinion of M. 

 Hermel, pulmonary, medullary, and cerebral congestions, which 

 he explains by the rebound produced by decompression; moreover: 



The decompression in itself (he says) does not produce all the 

 symptoms noted; the compression of the air in the caissons and the 

 harmful environment have much to do with it. (P. 203.) 



The work of M. Foley 21 is certainly the most original from the 

 standpoint of theory of all those we have already found and sum- 

 marized. Reading it is very stimulating, though not very easy; in 

 it, in fact, are found not only the account and the explanation of 

 the symptoms which attack the workmen in caissons, but also the 

 theory of the respiration of birds in the lofty regions of the air, the 

 operation of the swimming bladder in fishes, etc. Setting aside 

 these questions, which concern us only indirectly, we find M. Foley 

 trying to cast light on the inner cause of the symptoms which he 

 has observed by a study, which is hard to understand, of metabo- 

 lism, hematosis, and the physiology of the three nervous systems 

 by means of which "man (plant, animal and soul) governs his 

 multiple being." 



An example will indicate the nature of these considerations and 

 their conclusions. The author remarks that engineers go a long 

 time before feeling the ill effects of compressed air: 



That is because (he says) usually the former (engineers) nourish 

 their spinal cord and consequently stimulate their whole being with 

 memories, retained sensations, and because after that, to crush their 

 senses is to favor (so to speak) their ordinary mode of life. 



On the other hand, the second (workmen), forced to live and 

 work from day to day, to fashion and expend stimulation from hour 

 to hour (because they have never had time to accustom the primary 

 source of our organic activity to retained impressions), can nourish 

 their spines only with the materials of atmospheric contacts, always 

 real, always positive, always immediate: the very materials which 

 the excessive pressure prevents them from collecting. (P. 24.) 



