Theories and Experiments 463 



I confess that I think I must give up the task of summarizing in 

 a definite and intelligible statement the theories of M. Foley. Here 

 are a few quotations which I try to coordinate so as to cast a 

 little light on these obscurities of thought and style: 



As soon as the workmen are in the compressed air, their blood 

 becomes superoxygenated and their circulation tends toward its mini- 

 mum. At the same time, their nervous reserve, already so low, .... 

 falls still more. 



However they work, or in other words, their muscles and their 

 different mechanical organs, while being nourished by the blood, re- 

 quire stimulation from the spinal cord and plastic energy from their 

 controlling ganglia; from this triple compound of brain, spinal, and 

 sympathetic pulp; from this triple mixture of coordinating, vegetative, 

 and stimulating substances, the sympathetic chain first decides the 

 course of the blood, then regularizes it, and finally transforms it into 

 human flesh. 



How do the mechanical and metabolic governors, thus questioned, 

 reply to their subjects? 



But the spinal cord which no longer produces enough stimulation 

 refuses to give any, perhaps even demands to have some back from 

 the ganglia or plexus of the sympathetic chain! In their turn then, 

 they refuse to give any to their subjects, which nevertheless continue 

 to work, become empty of blood, then deteriorate, and finally are 

 unable to continue to operate. (P. 27.) 



So much for the phenomena caused by compression; now let us 

 turn to the decompression: 



We shall have the inverse of what the compression caused. (P. 44.) 



Little by little, the blunted senses of the caisson- worker revive; 

 little by little they send to the spinal cord more complete sensations; 

 little by little the apparatus of the spinal cord regains its power. 

 Little by little, it sends to the parts of the sympathetic chain, upon 

 which have been made such strong demands, the stimulation which 

 they need for their own recovery; and little by little, but in the final 

 step, these controlling nerves give the order which will send the 

 restorative tide to the muscles or other exhausted organs. 



Finally this command is dispatched. It leaves like a thunderbolt. 

 But generally too obedient to the principle (the reaction must equal 

 the action), it almost always causes an arterial congestion, the degree 

 and speed of which are proportional to its delay. (P. 28) . . . 



In summary, for the caisson-worker who has returned to open 

 air, we need to fear only too strong a nervoso-circulatofy reaction, a 

 shock to the circulation in this excessively violent change. (P. 45.) 



That is what M. Foley calls by the name of "post-caisson con- 

 gestion." 



"Thus," still according to M. Foley, "we have all the necessary 

 keys to the understanding of the different morbid phenomena which 

 may arise when one has left compressed air." (P. 29.) 



