NERVOUS TISSUES BLOOD 



81 



NERVOUS TISSUES 



Following the order given in the classification of tissues, the 

 nervous tissues should be studied at this point. But in laboratory 

 work it will be found more satisfactory to consider them in con- 

 nection with the histology of the central nervous system (see 

 page 216). 



BLOOD 



The human red blood -corpuscle is a flattened, bi- concave disk, 

 circular in outline, and from 7 p to 8 M (Woro inch) in diameter. It 



FIG. 50. CORPUSCULAR ELEMENTS OF HUMAN BLOOD (X 400). 



A. Colored corpuscles adhering by their sides rouleaux. 



B. The same crenated. 



C. The same shrunken. 



I). The same having absorbed water. 



E. The same still more swollen. 



F. The same with the plane C D, Fig. 57, in focus. 



G. The same with the plane A B, Fig. 57 in focus. 

 H. Colorless corpuscles. 



presents a mass of protoplasm destitute, as far as the microscope 

 shows, of nuclei, cell -wall, or any structure whatsoever. 



Certain changes in form result, after removal from the circula- 

 tion, viz.: 1. They may adhere by their broad surfaces forming 



