278 MICROBES AND TOXINS 



the objectors who, if he received a tetanus-suspected wound, 

 would riot call for a prophylactic injection of serum for 

 himself. 



It is necessary to avoid giving too small doses and, should 

 the wound fail to heal, to repeat the injection several times ; 

 of course, the surgical cleansing of the wound should never be 

 omitted. 



Antivenom Sera. — These are prepared by immunizing 

 horses, beginning with venom + calcium hypochlorite and ending 

 with pure venom. Eventually they can be made to support 

 80 lethal doses (2 grams of dried venom) at a single injection. 

 The immunization is a difficult operation to bring to a satis- 

 factory end ; frequently it is interrupted by serious accidents, 

 endocarditis, nephritis, and abscesses. It takes 16 months 

 of treatment to get a good serum from a horse (Calmette). 

 Antivenom serum is polyvalent, i.e., is prepared with several 

 species of venom. 



The quantity of serum required to save life increases with 

 the susceptibility of the animal and the delay in the application 

 of the remedy. As a rule 10-20 c.c. suffice to save a bitten 

 human being. 



Anticholera Serum. — Cholera is an acute intoxication 

 due to a poison elaborated by the vibrios in the intestine. 

 This toxin has been sought for and an antitoxic serlim 

 attempted. The serum prepared against the bacteria is not 

 active against the poison ; the principle of serotherapy is 

 thus quite different from the Ferran-Hafifkine method of 

 immunization. 



The cholera toxin prepared in 1896 by Metchnikoff, Roux, 

 and Salimbeni presented this peculiarity, that it resisted heating 

 to 100° C. for a quarter of an hour. Horses are prepared by 

 intravenous injections. 



Anticholera serum is still at the trial stage. Its only trial out- 

 side the laboratory was in 1909, during the epidemic of St. 

 Petersburg. The doses ought to be large, 150-350 c.c, given 

 100 c.c. at a time intravenously. There are cases so fulminant 

 as to defy almost any remedy. In the above trial cases, not 



