458 Historical 



peared very simple to Pravaz becomes strangely complicated after 

 the work of M. Fernet. (See page 249.) M. Bucquoy, who dwells 

 at length on the difference established by this physicist between 

 the oxygen chemically combined in the corpuscles and the oxygen 

 dissolved in the serum, says also: 



It is to the oxygen in simple solution that the changes in hematosis 

 observed in compressed air are due. 



In fact, the blood corpuscles in compressed air do not absorb a 

 greater proportion of oxygen than in the open air, because this pro- 

 portion has been shown to be independent of the pressure. 



On the other hand, the expenditure of oxygen which the blood 

 must make for the benefit of the respiratory combustions is as great 

 in compressed air as in open air, because these combustions are no 

 less active there than under ordinary atmospheric pressure. 



If then, in compressed air, the blood corpuscles supplied alone 

 and without compensation all the oxygen necessary for the combus- 

 tions, they would lose, as at ordinary pressure, a quantity of oxygen 

 sufficient to cause their arterial color to disappear, and when they 

 left the general capillaries, they would have the color of venous blood. 

 Now this is not the case; the corpuscles of venous blood are bright red 

 in the man who is subjected to compressed air. 



This fact, important from the physiological point of view, can be 

 explained in only two ways: 



Either the blood corpuscles supply for the respiratory combustions 

 under compressed air too small a portion of oxygen for their red color 

 to be perceptibly altered; in this case, the complement of oxygen 

 necessary for the combustions is taken directly from the portion of 

 this gas which is in simple solution in the serum, the quantity of 

 which, however, increases with the pressure. 



Or the corpuscles furnish all the oxygen necessary for the com- 

 bustions; in this second case, we are obliged to admit that they take 

 it from the serum as they lose it, since their color is hardly altered; 

 this hypothesis is the more probable. 



However it may be, the portion of oxygen dissolved in the serum 

 plays directly or indirectly an important part in the phenomena of 

 hematosis which go on under pressures greater than that of the atmos- 

 phere. It is this portion of oxygen which alone can explain the redness 

 of the venous blood always found by MM. Pol and Watelle, and by 

 M. Frangois too. It is wrong, therefore, that this portion of oxygen 

 absorbed should now be neglected and that variations in pressure 

 should be considered immaterial in regard to hematosis. (P. 50.) 



After this noteworthy page, I am sorry to find the adoption, 

 timid, it is true, and full of reservations, of the unsound theory of 

 the physical compression of the outer tissues, and of the conse- 

 quent ebbing of the blood into the interior of the body. Here is the 

 way, very original I admit, in which M. Bucquoy words it: 



