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HAND-BOOK OF PHYSIOLOGY. 



tity of such blood help, by the consequent rapid subsidence of the cor- 

 puscles, in the formation of the buffy coat already referred to. 



This tendency on the part of the red corpuscles, to form rouleaux, is 

 probably only a physical phenomenon, comparable to the collection into 

 somewhat similar rouleaux of discs of corks when they are partially im- 

 mersed in water. (Norris.) 



Mammals. Birds. Reptiles. Amphibia. Fish. 



FIG. 69.1 



1 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 re- 

 mains comparatively uniform, and thus they are, in some animals, much greater, in 

 others much less than the red corpuscles existing side by side with them. 



