STUDIES ON THE SERUM OF VACCINATED ANIMALS 31 



Frequently, as already mentioned, the injection of carmin, even 

 though repeated, gives no evident hypoleucocytosis. Under these 

 conditions there is no difference in the bactericidal property of the 

 blood before and after injection. Carmin itself has no effect on the 

 bactericidal substances, as may be shown by adding it to serum. 



The injection into normal animals of a rather large quantity of 

 serum from an unvaccinated animal brings about a distinct in- 

 crease in the bactericidal property of the serum of the animal. The 

 increased bactericidal property under these conditions, however, is 

 not to be compared with that caused by injecting the serum of vacci- 

 nated animals and, moreover, is not specific. The effect of injecting 

 normal serum is to increase slightly the normal bactericidal property 

 which is to be found in non-immunized animals, and this property 

 is by no means specific. We have tried to determine whether the 

 bactericidal property following these injections is more evident in 

 a fluid rich in leucocytes than in one containing only a few. 



EXPERIMENT 8. A small amount of blood was drawn from a 

 guinea-pig (leucocytes, 8000). From this blood was obtained 

 serum "A"; the same guinea-pig received, in the peritoneal cavity, 

 3 c.c. of serum from another normal guinea-pig. On the following 

 day a rubber ring was placed about the paw of this animal. Three 

 hours later the edema was removed and a small amount of blood 

 was also taken. This blood contained 6000 leucocytes and the 

 serum from it was labelled serum "B." Equal amounts of these 

 fluids were then inoculated with a 24-hour culture of cholera 

 (Oriental Prussia). 



The edema fluid removed at practically the same time as the 

 blood that formed serum "B" may be properly compared with this 

 serum. After 4J hours at body temperature there was no increase 

 in vibrios in serum " A"; there was a very marked decrease in serum 

 "B," but in the edema fluid there is an immediate and unrestricted 



