230 PASSIVE IMMUNIZATION 



chances are the better the longer the period of incubation, so that 

 the conclusion is not necessarily warrantable that recovery has 

 taken place in such cases because of the injection. The best that 

 we can say is that the treatment may possibly help, but that we 

 cannot always logically attribute recovery to the treatment. It 

 should be tried, but not too much should be expected. 



DYSENTERY 



While the attempts at prophylactic vaccination against infection 

 with the Shiga-Kruse bacillus have not led to very satisfactory 

 results (see p. 193), there is evidence to show that the use of the 

 corresponding antiserum exerts a beneficial influence upon the course 

 of the malady, when this has once developed. Regarding the mode 

 of action of the antisera which were first prepared by Shiga and 

 Kruse, there has been some controversy, it having being thought at 

 first that their effect was essentially bacteriolytic in nature. Subse- 

 quently, however, when it was shown by Kraus and Doerr that the 

 dysentery bacillus produces a true toxin, and that the same effect 

 could be obtained with an antiserum, produced with this as antigen, 

 the conclusion naturally suggested itself that the beneficial effects 

 reached with the older preparations, where unfiltered cultures includ- 

 ing the bodies of the bacilli represented the antigen, were probably 

 also owing to contained antitoxins. 



Preparation. The preparation of antidysentery serum is con- 

 ducted along similar lines as that of the other sera, which are used 

 for passive immunization, horses being employed as the antibody 

 producers. As in the immunization against diphtheria and tetanus 

 toxin a basic (Grund) immunity is first established by injecting a 

 certain quantity of antiserum together with, or twenty-four hours 

 preceding the introduction of the toxin, or the toxin cultures, after 

 which the process is continued with these alone. 



Dosage and Uses. The serum which is used for curative purposes 

 in Vienna is of such strength that 0.1 c.c. at most will protect a 

 rabbit weighing 1000 grams against a separate, though simultaneous 

 intravenous injection of a single lethal dose of the toxin. The 

 curative dose of such a serum for the human being varies between 

 10 and 20 c.c., which may be repeated several times in severe cases. 

 In extreme cases the French observers have used as much as 80 to 



