BLOOD SEBUM. 103 



also confirmed the finding of Fodor that after a while the blood 

 loses its germicidal properties and becomes a suitable culture 

 medium in which germs grow abundantly. 



Nissen continued this work under Flugge's direction and reached 

 the following conclusions : 



1. The addition of small quantities of sterilized salt solution or 

 bouillon to the blood does not destroy its germicidal properties. 



2. Cholera germs and Eberth bacilli are easily destroyed by fresh 

 blood. 



3. In a given volume of blood there is a maximum number of 

 bacilli which can be destroyed. 



4. Blood, the coagulability of which has been destroyed by the 

 injection of pepton, is still germicidal. 



5. Blood in which coagulation is prevented by the addition of 

 25 per cent, of magnesium sulphate has its germicidal properties 

 decreased. 



6. Filtered blood plasma from the horse is germicidal. 



At one time, Behring attributed the action of the blood of the 

 white rat on anthrax bacilli to its great alkalinity. He made a 

 number of titrations, by which he showed that the blood serum of 

 the rat is somewhat more alkaline than that of certain animals which 

 are more susceptible to anthrax, such as the rabbit, the guinea-pig 

 and the cow. This deduction is not justified, because there are 

 many other and more important points in which these animals differ 

 from the white rat than in slight diflFerences in the alkalinity of the 

 blood serum. Had he shown that the blood of the adult rat, which 

 is not susceptible to anthrax, is more alkaline than that of the 

 young rat, which is susceptible, his argument would have been more 

 plausible ; but even then it would not have deserved the dignity of 

 positive evidence. 



In 1890 Buchner and his students made a valuable contribution 

 to our knowledge of the germicidal properties of blood, and reached 

 the following conclusions : 



1. The germicidal action of the blood is not due to phagocytes, 

 because it is not influenced by the alternate freezing and thawing of 

 the blood, by which the leucocytes are destroyed. 



2. The germicidal properties of the cell-free serum must be due to 

 its soluble constituents. 



3. Neither neutralization of the serum, nor the addition of pepsin, 

 nor the removal of carbon dioxide gas, nor treatment with oxygen, 

 has any effect upon the germicidal properties of the blood. 



4. Dialysis of the serum against water destroys its activity, while 

 dialysis against 0.75 per cent, salt solution does not. In the diffu- 

 sate there is no germicidal substance. The loss by dialysis with water 

 must be due to the withdrawal of the inorganic salts of the serum. 



5. The same is shown to be the case when the serum is diluted 



