CHAPTER X 



[315] RAPID AND TEMPORARY IMMUNITY AGAINST MICRO- 

 ORGANISMS, CONFERRED BY SPECIFIC AND NORMAL 

 SERUMS, OR BY OTHER SUBSTANCES, OR BY MICRO- 

 ORGANISMS OTHER THAN THOSE AGAINST WHICH 

 IT IS DESIRED TO PROTECT AN ANIMAL 



Immunity conferred by specific serums. — Analogy of the mechanism of this immunity 

 with that observed in immunity obtained with pathogenic micro-organisms and 

 their products. — Part played by phagocytosis in the immunity conferred by 

 specific serums. — Influence of opium on the course of iQimuuisation by these 

 serums. — Stimulant action of specific serums. — Protective and stimulant action 

 of normal serums.— Influence of fluids, other than serums : broth, urine, physio- 

 logical saline solution, etc. 



Antagonism between anthrax and certain bacteria. 



We have seen how important in the study of acquired immunity 

 against micro-organisms is the demonstration of the protective power 

 of the body fluids. Without being absolutely general, this power is, 

 nevertheless, widely diffused and is found even in certain examples of 

 acquired immunity against micro-organisms belonging to the animal 

 kingdom. Up to the present I have refrained from doing more than 

 point out the presence, in the fluids of the immunised animal, of this 

 protective property and have studied it exclusively in relation to the 

 animal that produces it. We must now pass to the question : How 

 do the protective substances act in the animal which receives them 

 ready formed ? This immunity, which has received from Ehrlich the 

 name of 2^ctssive immunity against micro-organisms, must now be 

 examined. 



The study we now propose to enter upon is rendered much easier 

 from our study of the data acquired on the phenomena exhibited in 

 the animal vaccinated with micro-organisms or their products, data 

 already given in the preceding chapter. There is, indeed, a very 

 striking analogy between the two kinds of immunity, and though we 

 draw a sharp line of distinction between them, this is due to the fact 



