42 PHYSIOLOGY FOR THE LABORATORY. 



wrapping it in a moist cloth and then in tea-lead, leaving 

 one foot exposed. Cover the foot with a cover-glass, taking 

 care to have water beneath it. 



A tadpole is often easier to manage than a frog. Lay 

 a tadpole on a glass slide and keep it still by winding a 

 piece of moist cloth loosely around both the tadpole and 

 slide. Cover the end of the tail with a cover-glass, tak- 

 ing care that there is water under the cover-glass. 



Study under the microscope the circulation of blood 

 through the capillaries of the web of a frog's foot or the 

 tail of a tadpole. 



Notice : 



a. The capillaries, or small thin-walled blood-vessels. 



b. The red corpuscles carried along in the stream. What 

 is their shape and color? 



c. The white corpuscles. What is their movement and 

 position in the stream of blood? 



d. At a branch in the capillaries, see how the red cor- 

 puscles are bent out of shape, and then resume their normal 

 shape. 



e. The cells in the epidermis. 

 /. The black pigment cells. 



g. What is the color of the blood in a small vein or 

 artery ? 

 h. Sketch. 



