396 BLOOD AND LYMPH. 



blood to purplish red in venous blood, this variation in color being 

 dependent upon the amount of oxygen contained in the blood in 

 combination with the hemoglobin. Speaking generally, the func- 

 tion of the red corpuscles is to carry oxygen from the lungs to the 

 tissues. This function is entirely dependent upon the presence of 

 hemoglobin, which has the power of combining easily with oxygen 

 gas. The physiology of the red corpuscles, therefore, is largely con- 

 tained in a description of the properties of hemoglobin. 



Condition of the Hemoglobin in the Corpuscle. The finer structure 

 of the red corpuscle is not completely known. It is usually stated 

 that the corpuscle is composed of two substances, stroma and hem- 

 oglobin, together with a certain amount of water and salts and 

 also a certain amount of lecithin and cholesterin. The stroma is a 

 delicate, extensible, colorless substance that gives shape to the 

 corpuscles; it forms a mesh work or spongy mass in which the 

 hemoglobin is deposited. This latter substance forms the chief 

 constituent of the corpuscle, since it makes about 32 per cent, of the 

 weight of the normal corpuscle, and when dry from 90 to 95 per 

 cent, of the total solid material. According to another view the 

 corpuscles are vesicles with an external envelope or pellicle in 

 which lecithin and cholesterin are found, while the hemoglobin is 

 contained within.* Whichever view may be correct great interest 

 attaches to the presence of the lecithin and cholesterin, whether 

 these substances are found in an external membrane or in a stroma 

 permeating the corpuscle. According to Pascucci the lecithin and 

 cholesterin constitute as much as 30 per cent, of the dry weight of 

 the stroma, that is, of the portion of the corpuscle left after re- 

 moval of the hemoglobin. Such a large proportion of these two 

 substances is not found elsewhere in the body except in the myelin 

 sheath of the nerve fibers. It is believed that they play an impor- 

 tant role in maintaining the integrity of the corpuscles. Another 

 point that remains uncertain is the condition in which the hemo- 

 globin exists within the corpuscle. It is evidently not in solution, 

 since the amount present is too great to be held in solution in the 

 corpuscle, and, moreover, even a thin layer of corpuscles is far 

 from being transparent. Nor is it deposited in the form of crystals. 

 It is assumed, therefore, that it is present in a peculiar, amorphous 

 form, and Gamgee has shown that from its aqueous solutions the 

 hemoglobin can be obtained in an amorphous state by the action 

 of an electrical current. It is protected from the action of the 

 water within and without the corpuscle. In various ways, how- 

 ever, the relations of the hemoglobin within the corpuscle may be 



* For recent discussions upon the histological structure of the corpuscles, 

 see Weidenreich, "Anatom. Anzeiger," 1905, xxvii., 583; Ruzicka, ibid., 

 xxviii., 453; Schiifer, ibid., 1905, xxvi., 589. 



