﻿I.] THE FROG. 123 



/3. Their movements ; best seen if the slide be 

 gently warmed, by contact with a lighted match 

 or other heating agent They creep about in a 

 sluggish manner through the agency of the 

 above-named pseudopodia (amoeboid movement). 



y. Their size ; cf. generally with the red corpuscles. 



3. Their structure ; granular centrally, clear and 

 transparent peripherally: usually lodging one 

 or more clear round nuclei. 



e. Treat with acetic acid and magenta ; the nucleus 

 alone will be stained. It will be found to lodge 

 one or more small granular bodies (nucleoli). 



d. The microcytes. Very small bodies, for the most 

 part colourless, freely suspended in the plasma : 

 in shape variable; generally fusiform or ovoidal, 

 more rarely irregular. 



c. Coagulating blood. Allow a drop of blood to 

 coagulate upon a glass slide, taking care that it 

 does not dry up. Examine under a high power, 

 a. ^te plasma ; transformed into a colourless fluid 

 (serum] which is permeated by well-defined and 

 coagulate fibrin filament s. Note the course of 

 the latter ; they radiate from numerous foci and 

 anatomose irregularly. 



ft. The corpuscles; the red ones show a marked 

 tendency to arrange themselves along the lines 

 of coagulation ; the white ones are largely to be 

 found, together with microcytes, in the foci of 

 the fibrin filaments. 

 2. Epithelia. 



An epithelium consists of a layer of cells which 

 lines or invests a free surface : the epidermis cover- 



