486 Historical 



which we gave in the first chapter (page 395, et seq.), M. Gal 35 

 comes to the theoretical explanations, or, as he says, to the pa- 

 thogeny of the diseases caused by work in compressed air. 



He shrewdly distinguishes the cause of diseases with slow be- 

 ginning from that of symptoms which come on suddenly. For the 

 first, he accepts, he says, the explanation of M. Foley; but at least 

 he has the undeniable merit of expressing it in a comprehensible 

 form: 



We have seen that the blood of the caisson worker and the diver 

 is richly oxygenated, and it seems as if it would be hard for anemia 

 to occur under such conditions. But on the other hand, we have seen 

 that sensations perceived by the sense organs are much less distinct in 

 compressed air; therefore the spinal cord and the brain, since they 

 receive fewer stimuli, will produce less nervous energy, and the effect 

 of the sympathetic system upon the metabolism of the tissues will be 

 weaker than in the normal state. 



As long as the workman has not exhausted his reserve of nervous 

 influx, he will not suffer; the increase of his appetite will furnish/ his 

 blood with the materials which it needs to consume its oxygen; but 

 when he has exhausted his reserve, since production is less than the 

 expenditure, the functions of the sympathetic system will be carried 

 on imperfectly, and the patient will become mortally ill. Then he will 

 be most subject to the other diseases with sudden beginning and 

 immediate danger. 



As for the other diseases, they are all "due to congestion." On 

 that, says M. Gal, everyone is in agreement; but this is not the case 

 when their method of production is to be explained. 



On this point, he appears very eclectic. He considers as "pos- 

 sible," after my experiments, the opinion which attributes symp- 

 toms to a liberation of gas in the blood. But he prefers the ex- 

 planation of M. Foley about: 



The too violent reaction caused either by too sudden a decom- 

 pression, or by the lack of reaction in places where it usually takes 

 place, and where it is harmless, especially the skin. (P. 60.) 



We confess that this is anything but clear. A little farther on 

 he adds: 



In regard to the divers who died suddenly, the opinion of M. 

 Bucquoy and M. Leroy de Mericourt (he is referring to the efferves- 

 cence of gas) is very probably true. 



As for the other divers, who died sooner or later after the acci- 

 dent, they all had paraplegias. In all of them the lesion of the spinal 

 cord had occurred suddenly, which one can connect only with a con- 

 gestion, a hemorrhage in the substance of the spinal cord, or a 

 compression by hemorrhage in the vertebral canal. 



The cases of rapid cure observed and the invariability of double 



