THE BLOOD. 171 



has been controverted by the observations of Hannover (p. 103) and 

 Marchand; though Lehmann regards it as "completely proved." 

 The fact that chlorotic persons exhale as much carbonic acid as 

 those in health, may be explained by the supposition that, there 

 being a certain amount to be removed, each corpuscle absorbs more 

 than in health ; and the fact that the liquor sanguinis always ab- 

 sorbs a part of this gas. It is also very certain that a part of the 

 oxygen taken up by the blood-cells is only mechanically absorbed, 

 while a part (and probably the greater portion) acts chemically upon 

 their constituents. Lehmann found that after the inspiration of 

 oxygen the mineral substances and the hsematine in the blood-cor- 

 puscles increased, while the organic substances, and more especially 

 the fats, were considerably diminished ; the latter being destroyed 

 by oxidation, and their effete products being transferred to the 

 intercellular fluid, or, at all events, undergoing a considerable loss 

 of weight by the formation of carbonic acid and water. Heat is 

 also evolved in connection with the formation of the latter. 



The blood-cells, therefore, have a direct relation to the function 

 of respiration (aeration), and to the rapidity of the metamorphosis 

 and repair of the tissues. Hence, in the different species of animals, 

 we find a direct ratio between the normal amount of the blood-cells 

 in the blood, the activity of the aerating process, the waste of the 

 tissues and their repair (and, of course, the amount of food required), 

 and the natural (or organic) heat of the organism. But the oxygen 

 merely mechanically contained in the blood -cells also leaves the 

 latter in the capillaries and combines with the tissues, thus securing 

 their metamorphosis also, and again developing heat. 



At present, therefore, we must regard the blood-cells as the great 

 agents for effecting the dis-assirnilation of the tissues, and of the 

 blood itself. And since vital phenomena are impossible without a 

 constant metamorphosis of the molecules of the tissues manifesting 

 them, the blood-cells are indispensable in all the more active species 

 of the animal kingdom, and incidentally the natural temperature of 

 each is proportioned to their activity. Still, the corpuscles are only 

 the special, but not the sole carriers of oxygen ; the blood-plasma 

 also, to some extent, possessing that power. Hence the slow dis- 

 assirnilation and low temperature of the invertebrata may be secured 

 without them. In some of the latter, also, which possess a high 

 degree of activity (as the insects), the corpuscles are not required, 

 since oxygen is brought into direct contact with all their tissues 



