HISTOLOGY OF THE HUMAN RED KLOOD-CORPUSCLES. 



3. HISTOLOGY OF THE HUMAN RED BLOOD-CORPUSCLES. When 



observed singly, human red blood-corpuscles are biconcave circular discs of a 

 yellow colour with a slight tinge of green ; they seem to be devoid of an envelope, 

 are certainly non-nucleated, and appear to be homogeneous throughout. Each 

 corpuscle consists (1) of a framework, an exceedingly pale, transparent, soft 

 protoplasm the stroma ; and (2) of the red pigment, or hemoglobin, which 

 impregnates the stroma, much as fluid passes into and is retained in the interstices 

 of a bath-sponge. 



4. EFFECT OF REAGENTS.- (A) On their Vital Phenomena, The blood- 

 corpuscles present in shed blood or even in dcfibrinated blood, when it is 

 reintroduced into the circulation- retain their vitality and functions undiminished. 

 Heat acts powerfully on their vitality, for if blood be heated to 52 C, the vitality 

 of the red corpuscles is destroyed. Mammalian blood may be kept for four or 

 five days in a vessel under iced water, and still retain its functions; but if it be 

 kept longer, and reintroduced into the circulation, the corpuscles rapidly break up 



a proof that they have lost 

 their vitality. The red corpuscles 

 in freshly shed blood sometimes 

 exhibit a peculiar mulberry-like 

 appearance (figs. 5, 6, g, h). [This 

 is called crenation of the coloured 

 corpuscles. It occurs in cases 

 of poisoning with Calabar bean ; 

 and also by the addition of a 2 per 

 cent, solution of common salt.] 

 The blood of many persons crenates 

 spontaneously a condition as- 

 cribed to an active contraction of 

 the stroma, but it is doubtful if 

 this is the cause. The red cor- 

 puscles of the embryo-chick undergo 

 active contraction. 



(B) On their External Charac- 

 ters. (a) The colour is changed 

 by many gases. O makes blood 

 scarlet, want of O renders it dark 

 bluish-red, CO makes it cherry-red, 

 NO viulet-red. There is no difference between the shape of the corpuscles in arterial 

 and venous blood. All reagents (e.g., a concentrated solution of sodic sulphate), 

 which cause great shrinking of the coloured corpuscles, produce a very bright scarlet 

 or brick-red colour. The red colour so'produced is quite different from the scarlet- 

 red of arterial blood. Heagents which render blood-corpuscles globular darken the 

 blood, e.g. % water. 



[The contrast is very striking, if we compare blood to which a 10 per cent, solution of common 

 .salt has been added with blood to which water has been added. With reflected light the one 

 is bright red, and the other a very dark deep crimson, almost black.] 



(b) Formation of Rouleaux. A very common phenomenon in shed blood is the 

 tendency of the corpuscles to run into rouleaux (fig. 1, A, 3). 



Conditions that increase the coagulability of the blood favour this phenomenon, which is 

 ascribed by Dogiel to the attraction of the discs and the formation of a sticky substance. [The 

 cause of the formation of rouleaux is by no means clear. The corpuscles may be detached from 

 each other by gently touching the cover-glass, but the rouleaux may re-form. Lister suggested 

 that the surfaces of the corpuscles were so altered that they became adhesive. Norria made ex- 

 periments with corks weighted with tacks orpins, so as to produce partial submersion of the cork 



Fig. 5. 

 Crenation of human red blood-corpuscles. 



