348 Chapter XII 



of iodised solution becomes smaller and smaller compared with that 

 of the toxin, we are able, without difficulty, to vaccinate the most 

 susceptible animals and enable them to withstand considerable doses 

 of the pure toxin. By this method it is possible to immunise guinea- 

 pigs against the most active tetanus toxin. The method serves equally 

 well for the preparation of horses for injections of unmodified toxins. 

 For a longer or shorter time (according to the susceptibility of the 

 horse) toxins which are mixed with LugoFs iodised water are 

 injected. Having made sure of the resistance of the horse, larger 

 and larger quantities of pure, unmodified toxin may be introduced 

 with impunity. 



For the immunisation of mammals of all sizes (guinea-pigs, rabbits, 

 dogs, horses) against snake venom, Calmette, in his work at Lille, also 

 makes use of venom modified by chemical substances, but his method 

 difiers from those we have just described. During several weeks he 

 injects increasing quantities of venom, mixed mth decreasing quantities 

 of a solution of 1 : 60 of hypochlorite of lime. After this treatment the 

 animals become capable of tolerating fatal doses of unmodified venom 

 and can be injected with larger and larger doses. 



In recent years a method of vaccinating horses against certain 

 microbial toxins, and especially against the diphtheria toxin, by means 

 of mixtures of toxin and antitoxic serum, or with these two products 

 successively, has been introduced. Babes ^ was the first to extol 

 [366] this method as the best for obtaining a high and durable immuni- 

 sation. Afterwards, several other observers, amongst whom I may 

 cite Pawlowsky and Maksutow^, Palmirsky, and especially Nikanorofi"^, 

 took up this question, and communicated very encouraging results. 

 Von Behring* also found it very useful in certain cases. Thus, for 

 the vaccination of guinea-pigs against tetanus toxin, he recommends 

 the injection of a mixture containing antitoxin and an unneutralised 

 excess of toxin. Under these conditions he easily succeeds in im- 

 munising these small animals in cases where all other methods fail. 

 As a general method of vaccination against toxins, however, this 

 method has not fulfilled its promise, and Roux, who tried it several 

 times, was not at all satisfied with it. 



^ Bull Acad, de med., Paris, 1895, t. xxxiv, p. 216. 

 2 Ztschr.f. Hyg., Leipzig, 1896, Bd. xxi, S. 485. 



^ " On the preparation of a potent antidiphtheria serum," St-Petersbourg, 1897 

 (in Russian) [cf. Berl. klin. TVchnsch?\, 1897, S. 720]. 



* " Allgemeine Therapie der Infectionskrankheiten," Berlin u. Wien, 1899, S. 1093. 



