312 BIOLOGY OF PNEUMOCOCCUS 



lating in the blood stream at the time of treatment. Thus, in ani- 

 mals with negative blood cultures or with a low grade bacteriemia, 

 an amount of enzyme as small as five units might suffice to save the 

 life of the animal; with a bacteriemia of 100 to 1,000 organisms 

 per cubic centimeter of blood, twenty units might be necessary; 

 with a bacteriemia of 1,000 to 10,000 organisms fifty units were 

 required. In rabbits in which the bacteriemia exceeded 10,000 or- 

 ganisms per cubic centimeter a single injection of even one hundred 

 units failed to rescue the animal, although infections of this order 

 were successfully treated by repeated injections of large amounts 

 of enzymes over a period of days. 



Goodner and Dubos, in the discussion of their experimental 

 data, stated that, although the quantitative relation established in 

 the experiments was between the amount of enzyme and the number 

 of pneumococci present in the blood, the fundamental relation was 

 that existing between the quantity of enzyme and the total amount 

 of specific capsular polysaccharide present in the body ; and that 

 an index of the latter was the degree of bacteriemia. The authors 

 concluded that the enzyme is not a therapeutic agent per se, but 

 one which, by decomposing the capsular substance of pneumococci 

 and thus preparing the bacterial cells for phagocytosis — pianti- 

 cating them, to use Friel's term — initiates a process which the 

 body must be in condition to carry on if the animal is to recover. 

 Hence, in the use of the enzyme, this capacity of the body must be 

 reckoned with. 



EFFECT ON INFECTION INDUCED IN MONKEYS 



With this groundwork built, the next logical step was to apply 

 the enzyme to the treatment of animals higher in the zoological 

 scale which were suffering from experimental Type III Pneumococ- 

 cus infection. Francis, Terrell, Dubos, and Avery, 477 accordingly, 

 chose young adult monkeys — the Java monkey (Macacus cyno- 

 molgos) — as test animals, and infected the animals with a strain 

 of Type III Pneumococcus virulent for rabbits. They employed the 



