OBTAINING LARGE AMOUNTS OF ANIMAL BLOOD 



49 



By shaking vigorously the blood is defibrinated, if one desires to obtain 

 corpuscles, or the blood may be collected in a cylinder and defibrinated 

 by whipping with glass rods. 



It is usual, however, in large laboratories, to keep a sheep and 

 remove the blood as it may be required. Small amounts may be 

 obtained from the ear vein, larger quantities being secured from an 

 external jugular vein in the following manner: 



FIG. 25. METHOD OF BLEEDING A SHEEP FROM THE EXTERNAL JUGULAR VEIN. 



The operator is distending the vein by pressure over the base of the neck with 

 the left hand. When distended, the vein can usually be felt beneath the skin. The 

 needle here shown is reduced to a little more than half the actual size. 



1. One may do the bleeding alone, although the aid of an assistant 

 is usually necessary, especially if the animal is large and vicious. 



2. The sheep is thrown on its back, and the head is held on the knees 

 of an assistant seated on a low box or stool. 



3. The operator may straddle the animal to hold down the fore feet, 

 although this is not necessary unless the animal is vicious. 



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