260 PHAGOCYTOSIS— OPSONINS 



teria and of red blood corpuscles. Since the corpuscles are 

 normally 5,000,000 per c.mm., a simple calculation gives 

 the number of bacteria. The emulsion of bacteria is then 

 diluted so that a certain number of millions shall be contained 

 in each c.c, "standardized" as it is called, then heated to 

 the proper temperature for the necessary time and it is 

 ready for use. A preservative, as 0.5 per cent, phenol, tri- 

 cresol, etc., is added unless the vaccine is to be used up at 

 once. The amounts of culture, salt solution, etc., vary with 

 the purpose for which the \'accine is to be used, from one 

 or two agar slant cultures and a few c.c. of solution, when a 

 single animal is to be treated, to bulk agar cultures and 

 liters of solution as in preparing antityphoid vaccine on a 

 large scale. 



Agar surface cultures are used so that there will be as 

 little admixture of foreign protein as possible (see Anaphy- 

 laxis, p. 264 et seq.). Normal saline solution is isotonic with 

 the body cells and hence is employed as the vehicle. 



Vaccines are either "autogenous" or "stock." An "autog- 

 enous" vaccine is a vaccine that is made from bacteria 

 derived from the individual or animal which it is desired to 

 vaccinate and contains not only the particular organism but 

 the particular strain of that organism which is responsible 

 for the lesion. Stock vaccines are made up from organisms 

 like the infecti^'e agent in a given case but derived from 

 some other person or animal or from laboratory cultures. 

 Commercial vaccines are "stock" vaccines and are usually 

 "polyvalent" or even "mixed." A "polyvalent" vaccine 

 contains several strains of the infective agent and a "mixed" 

 contains several different organisms. 



Stock \'accines have shown their value when used as pre- 

 ventive inoculations, notably so in typhoid fe\-er in man, 

 anthrax and black-leg in cattle. The author is strongly of the 

 opinion, not only from the extended literature on the sub- 

 ject, but also from his own experience in animal, and espe- 

 cially in human cases, that stock vaccines are much inferior 

 and much more uncertain in their action when used in the 

 treatment of an infection, than are autogenous vaccines. This 

 applies particularly to those instances in which streptococci, 

 micrococci, and colon bacilli are the causative agents, but to 



