CH. XXVI. ] 



THE RED CORPUSCLES 



419 



The corpuscles of all mammals, wibh the exception of the camel 

 tribe, are circular and biconcave. They are generally very nearly 

 the size of human red corpuscles. They are smallest in the deer 

 tribe and largest in the elephant. In the cameliclse they are 

 biconvex. In all mammals the corpuscles are non-nucleated, and 



FIG. 348. The above illustration is somewhat altered from a drawing by Gulliver, in the Proceed. 

 Zool. Society, and exhibits the typical characters of the red blood-cells in the main divisions of the 

 Vertebrata. The fractions are those of an inch, and represent the average diameter. In the case 

 of the oval cells, only the long diameter is here given. It is remarkable, that although the size of 

 the red blood-cells varies so much in the different classes of the vertebrate kingdom, that of the 

 white corpuscles remains comparatively uniform, and thus they are, in some animals, larger, in 

 others smaller, than the red corpuscles. 



in all other vertebrates (birds, reptiles, amphibia, and fishes) the 

 corpuscles are oval, biconvex, and nucleated (fig. 348) and larger 

 than in mammals. They are largest of all in certain amphibians 

 (amphiuma, proteu^). 



The red corpuscles are not all alike, for in almost every specimen 

 of blood may be also observed a certain number of corpuscles smaller 



