1 AIM UN IS ATI ON AGAINST B. TYPHOSUS. 339 



animals appear, however, either to have died sooner or 

 survived much longer than in Sanarelli's experiments. 

 Martin found that if the B. coli and B. enteritidis had 

 their virulence exalted results similar to those seen with 

 the B. typhosus were obtained. He further points out 

 that not only the poisons of these three related bacilli but 

 those of ricin and abrin produce similar results. 



The general conclusions to be drawn from all these 

 observations is that there exist in the bodies of typhoid 

 bacilli toxic bodies, that in artificial cultures these do not 

 pass to any great degree out into the surrounding medium, 

 that though they produce effects on the intestine there is 

 evidence that these are not peculiar to the toxines of the 

 B. typhosus. As to the nature of the typhoid toxines we 

 know nothing. Martin has, however, found that in the 

 case of the typhoid bacillus there is very little digestive 

 action, such as occurs with the bacilli of diphtheria and 

 tetanus. 



The Immunisation of Animals against the Typhoid 

 Bacillus. In considering this question we must note (i) 

 immunisation against the living bacilli ; (2) immunisation 

 against their toxines; and (3) the relations between these 

 two conditions. Earlier observers had been successful in 

 accustoming mice to the typhoid bacillus by the successive 

 injections of small and gradually increasing doses of living 

 cultures of the bacillus. Later, Brieger, Kitasato, and 

 Wassermann, in their joint researches on immunity, obtained 

 further results. One of the general principles on which 

 they worked was that a bouillon made from an extract of 

 the thymus gland contained bodies which were inimical to 

 the virulence of various bacilli, though the medium was 

 sufficiently nutritive to permit of their multiplication. 

 Applying this principle to the B. typhosus, they grew a 

 culture very virulent to mice for three days on such a 

 bouillon, and then killed the contained bacilli by heating 

 at 60 C. for fifteen minutes. A small quantity was then 

 injected into each of a series of mice without fatal effect. 

 Ten days later it was found that these mice could tolerate 



