THE BLOOD. 121 



nline, which spectra can be produced by alternately taking 

 away and restoring the oxygen of the solution of blood, we 

 bring a new element to the explanation of the difference of 

 color in arterial and venous blood. This difference is not 

 due only to changes in form in the globules, for these changes 

 in color, which correspond with the differences in the spec- 

 trum of arterial and venous blood, are, like these, the result 

 of alternations of oxidation and of reduction of the hemo- 

 globuline, so that the arterial and venous blood represent the 

 two states of oxidation and reduction of the coloring matter 

 of the blood. 



The physiological function of the red globules consists 

 entirely in the absorption of oxygen which they then impart 

 to the tissues. They are the receptacles, the condensing 

 apparatus of this gas, similar, so to speak, to coal and to the 

 sponge of platina. In traversing the pulmonary capillaries 

 they borrow the oxygen from the outer air, and then carry it 

 to the different parts of the system, especially to those which 

 consume this gas in large quantities, that is, the nerve glob- 

 ules, the nerves, and the muscles. These elements give 

 back, in exchange for the oxygen which they receive, a nearly 

 equal quantity (see respiration) of carbonic acid, a small part 

 of which remains in the blood globules, the larger part being 

 dissolved in the liquid, or liquor of the blood. 



The functions of the blood globules are thus principally 

 mechanical, on account of the movements to which they are 

 subjected, and of their connection with the gaseous inter- 

 change. We may also say that the principal object of these 

 functions is to excite or support the nervous system, as the 

 nerves can exist only where the blood globules are properly 

 constituted, and contain the necessary quantity of oxygen 

 gas. Thus no animal can lose, unharmed, more than one-fifth 

 of its blood, or of the mass of its cruor. If it does, it suc- 

 cumbs, with symptoms which resemble those attending a 

 nervous fever, such as prostration, loss of sensibility, buzzing 

 in the ears, deafness, convulsive movements, dyspnoea, and 

 death. The transfusion of fresh blood, defibrinated (in one 

 word, the transfusion of globules), will remove these symp- 

 toms, and bring back life, if done in time ; the transfusion of 

 the liquor alone will not suffice. 



The transfusion of blood consists, essentially, in bringing a 

 new supply of blood globules. This operation responds 

 neither to the exaggerated hopes of the restoration of youth, 

 of the cure of madness, etc., nor to the unreasonable fears 



