52 



STUDIES IN ADVANCED PHYSIOLOGY. 



Fig. 8. RED BLOOD CORPUSCLES. (After Frey.) 



1, human; 2, camel; 3, pigeon; 4, proteus; 5, salamander; 6, frog; 7, snake; 8, lani- 

 prey. (a, surface view; l>, side view.) (Drawn on same scale.) 



mals. With the exception of the camel, whose corpuscles 

 are slightly oval, all the corpuscles of the mammals are 

 round. They are further easily distinguished from those of 

 the lower animals, as in the latter the red corpuscles 

 possess a distinct nucleus. It is interesting that in the em- 

 bryonic state of the human being nucleated corpuscles 

 occur. 



2. Color. When seen singly the corpuscles do not 

 appear red but have a yellowish tint, sometimes shading 

 over into a greenish. This is due, of course, to the dilution 

 of the coloring matter when a single corpuscle is looked at. 

 But the color of ordinary blood is not alone due to the 

 actual color of the haemoglobin, but also to the reflection of 

 the light from the innumerable little concave mirror-like 

 surfaces of these corpuscles. This explains why blood 

 becomes "laky" in color when the coloring matter is 

 extracted from the corpuscles and dissolved in the liquid. 

 Such laky blood becomes transparent and dark in color. If, 

 on the other hand, certain mineral salts be added to the 

 blood which cause the corpuscle to shrink, the blood 



