32 PHYSIOLOGY FOR THE LABORATORY. 



Notice : 



a. The red corpuscles. What is their shape as shown 

 by a surface and an end view ? Do you find a nucleus ? 



b. The white corpuscles (stained in the preparation). 

 What is their size and shape? What is the nature of 

 their contents? Have they any nucleus? 



c. Sketch a corpuscle of each kind greatly enlarged. 



III. THE BLOOD OF OTHER ANIMALS. 



A few drops of a pigeon's or a hen's blood may be 

 obtained and compared with the two kinds already studied. 



B. The Clotting of Blood. 



Materials. Fresh blood from the market, or a frog. Chloroform. 

 Cotton batting. 



Apparatus. Test-tube. Bell-jar. 



I. THE CLOT. 



Fresh blood of an animal recently killed may be had of 

 the butcher, or a frog may be killed and the blood col- 

 lected. To kill a frog, place it under a bell-jar with some 

 cotton batting saturated with chloroform. Wait until the 

 frog is stiff before dissecting. Then make an incision 

 along the ventral median line, cutting through the breast- 

 bone. Cut the blood-vessels leading to and from the heart 

 close to the latter, and collect the blood in a test-tube. 

 Pour out some of the blood into a smaller test-tube and 

 allow it to stand, taking care to cover it so that it cannot 

 dry. Watch it until changes take place. In case the 

 blood is obtained of the butcher, some of it should be 

 poured in a glass jar and allowed to coagulate. 



