BLOOD. 



473 



63. t per cent, of the blood is constituted by the plasma, and 36.3 per 

 cent, blood-corpuscles. The red corpuscles, as already mentioned, are 

 heavier than the other constituents of the blood, and are the cause of 



Fig. 173.-Bloob-Coepusci.es of Different Animals. (Thanhoffer.) 



1, proteus ; 2. rana esculenta : a, upper view ; 6. white blood-corpuscle ; r, side view of red blood-cor- 

 puscle ; 3, triton: 4. snake; 5. camel; 6, turtle; 7, salamander; 8, carp; 9, cobitis fossilis; 10, cuckoo; 

 U, chicken ; 12, canary-bird ; 13, lion ; 14, elephant ; 15, man : a, upper view ; b. crenated form ; c, color- 

 less corpuscle ; 16, ljorse, the cells arranged in rouleaux ; 17, hippopotamus, upper view. 



the color and opacity of the blood ; their specific gravity may be placed 

 at about 1090. If water is added to blood, it appears darker in reflected 

 light, but is more transparent. This depends upon the change in shape 



•A* £ 



Fig. 174.— Red Blood-Corptjscles, showing Various Changes in Shape. (Landois.) 



a, b, normal human red corpuscle, with the central depression more or less in focus : c, d, e, mulberry 

 forms; g, h, crenated corpuscles; k, pale, decolorized corpuseles; i, stroma;/, a frog's corpuscle, partly 

 shriveled, owing to the action of a strong saline solution. 



of the red blood-cells: as they imbibe water they swell up, and so reflect 

 less light, and at the same time the co-efficient of refraction differs less 

 than normal from that of the blood-serum. On the other hand, if salt 



