148 PROTEIN POISONS 



Rabbits No. 4 and 5 had the same treatment as did Nos. 

 2 and 3, and seven days after the last dose each received 

 5 c.c. of a twenty-four-hour culture of the living colon 

 bacillus without a fatal result. A control which received 

 the same amount of the same culture died within five hours. 



When we turn our attention to the symptoms which 

 follow the injections of living cultures of the colon bacillus 

 into animals which have been actively immunized with the 

 split products, we find that the clinical picture differs 

 materially according as to whether they have been treated 

 with the toxic portion or with the residue. As has been 

 previously mentioned, the symptoms which are observed 

 in a pig immunized with the toxic part are apparently 

 identical with those which one sees in a normal animal 

 after inoculation with a non-lethal dose of the living bacillus. 

 The picture which is obtained on inoculation of animals 

 rendered immune by previous treatment with the residue 

 is, however, quite different. In this case the animals 

 become apparently very ill within an hour after inoculation 

 with the living germ. Indeed, so noticeable was this fact 

 and the treated pigs appeared so much sicker than did the 

 controls that our first thought was that we had in some 

 manner increased their susceptibility to subsequent infec- 

 tion by treatment with the residue. However, after from 

 six to eight hours the treated animals appeared in much 

 better condition and eventually recovered, whereas the 

 controls invariably died. The temperature of the treated 

 animals runs a course entirely in accord with the symptoms. 

 Thus in a pig which had received 290 mg. of the residue, 

 and subsequently was inoculated with 1 c.c. of a twenty-four- 

 hour culture, the temperature fell from 100 to 95 F. within 

 four hours, and by six hours had once more begun to rise, 

 as is illustrated in Fig. 9. 



The difference between the behavior of animals treated 

 with the toxic part and those which have been treated with 

 the residue toward cultures of the living germ is easily 

 explained if we consider the fact that in the first case we 

 are dealing with an animal which has acquired a certain 



