484 Historical 



why "they occur in the special nervous center rather than in the 

 cerebral mass," and he answers: 



The cranial case and the vertebral column form two coverings 

 which are equally incompressible; consequently, when the blood is 

 driven from the entire surface of the body and the compressible 

 splanchnic cavities, it must tend to congest the cerebro -spinal axis. 

 The circulatory system of the spinal cord, compared to that of the 

 brain, is infinitely richer, as the congestions show; finally, in the 

 sponge fisherman, it is the legs which become most weary, because 

 during his stay under water, he must constantly walk and climb up 

 and down the rocks. Perhaps these are the causes which account for 

 the fact that the spinal cord is the favorite seat for the symptoms. 

 We give this explanation, of course, with the greatest circumspection. 



M. Bouchard, 34 in his study of the Pathogeny of Hemorrhages, 

 includes the symptoms of compression and decompression, which 

 he considers as due to abdominal, spinal, and cerebral congestions 

 and hemorrhages. The manner in which he imagines they are pro- 

 duced is very interesting; it is borrowed, he says, from M. Marey: 



When the compressed air makes its way into the lungs, there is 

 no longer any tendency for a vacuum to be made in the chest, as in 

 the case of naked divers; pulmonary congestions are no longer to be 

 feared. However the abdomen is normally distended by gases; since 

 the outer air does not enter the intestine, these gases are compressed 

 and occupy a volume which is in inverse proportion to the intensity 

 of the compression. The volume of the abdomen will become four 

 times less, if the pressure is four atmospheres. Then the wall is 

 everywhere crowded against the spinal column and thus forms an 

 anterior concavity. But this wall is not inert; it tends to become 

 straight again, through its tonicity and even its contractility, and con- 

 sequently to lessen in the abdomen the pressure which had been 

 counterbalanced by this pushing back of the wall; it acts like a huge 

 cupping-glass, which would attempt to accumulate in the abdomen 

 the blood from the other organs. And in fact, general anemia is 

 produced. 



This plethora of blood in the abdominal organs is not, however, 

 the cause of hemorrhages, except perhaps in the spleen. 



So much for the explanation of the visceral congestions during 

 the compression. But at the time of the decompression, an inverse 

 phenomenon would take place: 



It is at the time of the decompression that the hemorrhages occur, 

 at the moment when the intestinal gases, regaining their volume and 

 distending the abdominal wall in the opposite direction, cause the 

 organs of the belly to undergo a positive pressure which will drive 

 out the blood stored in their interior, and direct it suddenly towards 

 the other organs, the vessels of which, since they have lost their 

 tonicity, .... do not adapt themselves quickly to this sudden inroad. 



