THE BLOOD. 243 



process. The size as well as the number of the corpuscles in different 

 classes of animals appears to be directly related to the activity of the 

 respiratory process. ^-In those animals in which the corpuscles are 

 small and numerous and the total superficial area large, respiration 

 is active, the quantity of oxygen absorbed is large, and the energy ^ 

 evolved through oxidation great.***In those animals, on the contrary, 

 in which the corpuscles are large and relatively few in number, the 

 reverse conditions obtain. ^.This is in accordance with the fact that 

 the superficial area of any given volume of substance is increased in 

 proportion to the extent to which it is subdivided. 



The superficial area of a single human red corpuscle has been 

 estimated at 0.000128 sq. mm. If the number of corpuscles in i 

 cubic millimeter of blood averages 5,000,000, the superficial area 

 would amount to 640 square millimeters ; and if the amount of blood 

 in the body of a man weighing 75 kilos is taken as one- thirteenth of 

 this weight, that is, 5769 grams (5463 c.c.), the total area of the 

 corpuscular surface will amount to 3496 square meters. 



Life-history of Red Corpuscles. In the performance of their 

 functions the red corpuscles undergo more or less disintegration and 

 final destruction; but as the average number is maintained under 

 normal physiologic conditions, there must be a constant renewal from 

 day to day. The evidence of destruction of red corpuscles is fur- 

 nished by the presence in the blood in various situations of the body 

 of a pigment containing iron and the presence of pigments in the bile 

 and urine, all of which are believed to be derivatives of effete hemo- Jf 

 globin. Vrhe blood-pigment (hematin), which contains the iron_.ol r 

 the hemoglobinj^s found in the capillaries of the hver, in the cells of 

 the splenic pulpT and in the niarrow of the bonesT Whether the 

 presenceoiTrTr pigment in these organs is a prooi-that the corpuscles 

 are destroyed here, or whether they are to be regarded merely as 

 agents concerned in the further reduction and elimination of the 

 hematin, is uncertain.^ The genetic relationship between bile-pig- 

 ment and hemoglobin is shown by the fact that any artificial destruc- 

 tion of hemoglobin or its injection into the blood is attended by an )J, 

 increase in the quantity of bile-pigment eliminated\ It appears also 

 from chemic considerations that the hemoglobin will undergo cleavage 

 into a globulin body and hematin, which by the loss of its iron is readily 

 converted into the bile-pigment, bilirubin. The amount of this latter 

 pigment may therefore be taken as an index of the extent of corpus- 

 cular destruction. 



This gradual decay of corpuscles as well as the losses occasioned 

 by hemorrhages necessitate a continuous formation of new cor- 

 puscles, so that the normal number may be maintained. The rapidity 

 with which corpuscles may be renewed, in the woman at least, is 

 shown by a computation of Mr. Charles L. Mix. A woman loses 



