64 
PRINCIPLES OP BACTERIOLOGY 
food for) are substances which so act on bacteria as to 
make them more easily destroyed by the white blood 
cells (leucocytes), as will be mentioned later. 
It is very important to remember that antitoxins are 
formed by injection of not only bacteria and their prod¬ 
ucts, but of many other poisons of plant and animal 
origin. 
Likewise lysins, agglutinins and precipitins may be 
produced by injection of numerous different sub¬ 
stances; one of the most common examples is the injec¬ 
tion of one animal with the red blood cells of another, 
whereupon the former will produce antibodies (lysins) 
against the red blood cells of the latter; such antibodies 
instead of being called bacteriolysins are called 
hemolysins (“blood dissolvers”). 
V. Application of Hemolysis and Agglutination to 
Blood Transfusion Tests 
Before transfusion of blood is resorted to in the treat¬ 
ment of such conditions as severe hemorrhage, pernicious 
anemia, shock, etc., the blood of the patient (who now 
is called “the recipient”) and that of the one who gives 
the blood (“the donor”) must be “matched,” that is, 
we must ascertain that neither one of the two bloods 
dissolves (hemolysis) or clumps (agglutinates) the other. 
The blood is secured from both the donor and the 
recipient either from a vein by means of a syringe or 
from a finger by means of a spring lancet; a part of each 
blood is received into a small test tube and allowed to 
clot; the remainder of each blood is received into a 
test tube containing about 10 c.c. of normal salt solution 
(0.85% N'aCl) or 2% sodium citrate solution. 
Two c.c. of blood from each—donor and recipients— 
are sufficient for the test. 
