886 Experiments 



the bubbles of free gases escaping under mercury from the blood 

 of a dog placed at 3 atmospheres. 



It is evident that in the dog of Experiment DXXXIX, which 

 was some days afterwards decompressed from 5 atmospheres with- 

 out symptoms, the blood in circulation contained fine bubbles. But 

 they could pass through the capillaries without obstructing the cir- 

 culation, and probably were dissolved more or less rapidly. 



The presence of such bubbles would be enough, I think, even 

 if there were no stoppage of the circulation, to explain, on the 

 basis of irritation of the tissues, the slight symptoms of workmen 

 in caissons, the "puces" (fleas) and the "moutons" (sheep), dis- 

 cussed in the historical part. We therefore understand the risks 

 run by these workmen, whose paralysis or death at these limits 

 depends upon the size of a bubble of gas. It is not surprising then 

 that symptoms, slight in some and fatal in others, appeared after 

 too sudden decompression from about 4 atmospheres. 



But the presence of bubbles of nitrogen in the blood, irritating 

 the tissues in contact with them, when they are small enough to 

 traverse the capillaries, or causing more serious and more lasting 

 symptoms, when they interrupt the circulation, does not constitute 

 the only danger to which animals rapidly decompressed are ex- 

 posed, nor is it perhaps the most dangerous. 



Indeed, the very tissues of the organism, which are impregnated 

 with liquid, and the liquids other than the blood are laden with a 

 growing proportion of nitrogen, from contact with the blood which 

 is supersaturated with it. And when the decompression occcurs, 

 these gases must necessarily return to a free state, distending and 

 even lacerating the tissues from which they escape. Experiments 

 DXXXVI, DLVIII, DLIX, DLX, and DLXIII have shown us gases 

 in the subcutaneous or intermuscular tissue, in the liquids of the 

 eye, in the cerebro-spinal liquid, in the spinal cord, etc. Experi- 

 ment DLVIII, in which the explosion took place, is quite remark- 

 able in this reference; the subcutaneous emphysema was such that 

 the dog had become absolutely cylindrical. Let us mention par- 

 ticularly also Experiment DXXXVI, in which in a pregnant bitch 

 we found gas not only in the blood vessels and tissues of the ani- 

 mal, but also in those of the foetuses, and even in the allantoid 

 liquid; the amnion, which is much less vascular, contained none. 



These gases, imprisoned in the meshes of the tissues, must, when 

 they do not cause death, be the cause of pains and local swellings, 

 and it is evidently to them that we must ascribe the muscular 



