STUDIES ON THE SERUM OF VACCINATED ANIMALS. 73 



preparations were made with vibrio, edema fluid and normal serum, 

 and transformation takes place: 



It is evident, then, that the edema fluid contains enough of the 

 preventive substance, of which a very small amount is necessary 

 to produce the phenomenon, and it may be added that it is difficult 

 to obtain an edema fluid without leucocytes. Even if there were 

 no leucocytes present and it were distinctly proved that leucocytes 

 are necessary for the presence of the preventive substance, it might 

 well be that a certain amount of it would be liberated during life 

 into the fluids of the body and eventually be excreted; it is well 

 known, indeed, that the preventive power falls rapidly when injec- 

 tions are stopped. But there is a body fluid that under normal 

 conditions is almost entirely deprived of cells, that is, the aqueous 

 humor. It may be shown that the aqueous humor in vaccinated 

 guinea-pigs has neither bactericidal nor preventive power. Whether 

 mixed with normal serum or with immunized goat serum, aqueous 

 humor produces no change in the vibrio. 



Cholera (Eastern Prussia) + normal G. p. serum 



+ preventive goat serum + normal G. p. serum. 



+ vaccinated G. p. aq. humor + normal G. p. serum 



+ preventive goat serum + vaccinated G. p. aq. humor 



It would seem, therefore, that the function of leucocytes in the 

 genesis of the specific properties of serum is well determined. 



In a consideration of bactericidal and preventive power we have 

 covered several of the more important body fluids. We may now 

 consider intestinal transudate from the same point of view. In 

 human cholera the vibrio is not a parasite in the tissues; it invades 



