STUDIES ON THE SERUM OF VACCINATED ANIMALS. 41 



(6) Smaller guinea-pigs. No. 1 (240 grams) received 0.2 of a 

 cubic centimeter of serum; No. 2 (265 grams), 0.2 cubic centimeters 

 of edema. These two animals and a control, No. 3 (300 grams), 

 were given to of a culture on the following day. The control (No. 

 3) and the guinea-pig that had received edema fluid were found 

 dead the following day. The guinea-pig that had received serum 

 withstood the infection. 



(c) A guinea-pig (325 grams) received 0.2 of a cubic centimeter 

 of serum. Guinea-pig No. 2 (350 grams), 0.2 of a cubic centimeter 

 of edema. Control guinea-pig (340 grams). Each received ttj of 

 a culture the evening of the same day. The following morning the 

 control and the animal that had received edema fluid were found 

 dead. The guinea-pig that had received serum died two days later, 

 probably of intoxication, since the heart's blood was sterile; the 

 peritoneal exudate was found to contain a rather large number of 

 leucocytes, which were very infrequent in the exudates from the 

 other two animals. 



Let us now consider the preventive value of two samples of serum 

 from the same animal, containing different numbers of leucocytes. 



Experiment 13. A guinea-pig that had been well vaccinated 

 against Massaouah was given an injection of carmin. A specimen 

 of blood was taken before and after injection (serum "A" before, 

 number of leucocytes 11,000; serum "B" after injection, number 

 of leucocytes 3000). The bactericidal properties of the two sera 

 were studied by the method already described. 



(a) Guinea-pig No. 1 (360 grams) received 0.3 of a cubic centi- 

 meter of serum "A." Guinea-pig No. 2 (390 grams) received 0.3 

 of a cubic centimeter of serum "B." Control guinea-pig (455 

 grams). The following day each animal received xV of a Massaouah 

 culture. The control alone died. 



(b) Guinea-pig No. 1 (345 grams) received 0.2 of a cubic centi- 

 meter of serum "A"; guinea-pig No. 2 (375 grams), 0.2 of a cubic 

 centimeter of serum "B." Control (440 grams). The following 

 day each animal received tV of a culture. The control and the 

 animal that received serum "B" (containing the smaller number 

 of leucocytes) were found dead the following morning. The guinea- 

 pig that received serum "A" died the same day in the afternoon; 

 the peritoneal exudate from this animal was the richest in leucocytes. 



