116 



CIECULAR AND ELLIPTIC CELLS. 



disc and not to a nucleus. The sac of each disc is elastic, so that it can 

 Pro erties and ^ e swo ^ en ^7 water until it becomes convex or even globu- 

 sizeoftheper- lar, or by immersion in thick sirup may be made to shrink, 

 :el ' effects arising from the endosmotic infiltration or exudation 

 through its wall. When passing through the fine capillaries in the 

 course of the circulation, the cell, by reason of this elasticity, can make 

 its way through very difficult passages, extending itself into a cylindroid 

 form, or by bending, but it recovers its original shape as soon as relieved 

 from pressure. The average diameter of the cell is estimated at 32 * OQ of 

 Fig. 42. an incn the extremes being ^J^, and-^^i^. 



The thickness of the cell is about -12400 of 

 an inch. The cell owes its color to ha3ma- 

 tin, which exists in its interior in a state of 

 solution, and associated with globulin. 



The facts mentioned in the preceding par- 

 agraph are illustrated by the annexed en- 

 graved photographs. Fig. 42 represents hu- 

 man blood-ceils. Their form is circular : they 

 have a central depression, but no nucleus. 

 Fig. 43 represents the elliptic nucleated 

 blood-cells of the frog, with here and there, 

 Fig. 44 represents .the endosmotic action of 



Human blood-cells magnified 500 diam 

 eters. 



at a a, chyle corpuscles. 



Fig. 43. 



Fig. 44. 



Elliptic blood-cells of frog magnified 250 diame- 

 ters. 



Action of vrater on elliptic cells. 



water on these cells. Fig. 45, the action of acetic acid in darkening or 

 concentrating the nucleus. In Fig. 46 we have an illustration of the 

 size and appearance of the blood-cell in a reptile, the photograph from 

 which this figure was taken having been made under the same magni- 

 fying power as that employed in obtaining the photograph of human 

 blood. 



