320 TYPHOID FEVER. 



bacilli which produce the toxines. Similar results have been 

 obtained in the case of cholera. It therefore appears that 

 the toxines of the typhoid bacillus stimulate the tissues of an 

 animal to produce bodies which act, directly or indirectly, 

 as germicides to the bacilli. What these are, when and how 

 they are produced, we do not at present definitely know. 



The Pathogenicity of the B. coli and its Relation to that of the 

 Typhoid Bacillus. We have already seen that the B. coli is probably 

 responsible for the occurrence of some of the abscesses which follow 

 typhoid fever. It is also apparently the cause of many cases of summer 

 diarrhoea (cholera nostras), and of infantile diarrhoea. Its numbers in 

 the intestine are greatly increased during typhoid fever, and also 

 during any pathological condition affecting the intestine. Intraperi- 

 toneal injection in guinea-pigs is occasionally fatal. Subcutaneous 

 injection results in local abscesses, and sometimes in death from 

 cachexia. Sanarelli found that the B. coli isolated from typhoid stools 

 was much more virulent than when isolated from the stools of healthy 

 persons. He holds that the increase in virulence is due to the effect 

 of the typhoid toxines, and devised an ingenious experiment which 

 seems to prove this point. This increased virulence of the B. coli in 

 the typhoid intestine makes it possible that_ some of the pathological 

 changes in typhoid may be due, not to the typhoid bacillus, but to the 

 B. coli. Some of the general symptoms may be intensified by the 

 absorption of toxic products formed by it and by other organisms. The 

 question has been raised as to whether the lesions produced in guinea- 

 pigs by such virulent B. coli can be distinguished from those of the B. 

 typhosus. Sanarelli holds that they can, and that the former partake more 

 of the nature of a septicaemia with pleurisy, pericarditis, and peritonitis ; 

 while in the latter the disease is more concentrated in the lymphatic 

 tissue of the intestine. He admits, however, that the differences are 

 more in degree than kind. Differences of behaviour of the two bacilli 

 in connection with their pathological effects, have been brought forward 

 as confirmatory of the fact of their being distinct species. Thus 

 Sanarelli accustomed the intestinal mucous membrane of guinea-pigs 

 to toxines derived from an old culture of the B. coli, by introducing 

 day by day small quantities of the latter into the stomach. When 

 a relatively large dose could be tolerated, it was found that the 

 introduction in the same way of a small quantity of typhoid toxine was 

 followed by fatal result. Pfeiffer also found that while the serum of 

 convalescents from typhoid paralysed the typhoid bacilli, it had no 

 more effect on similar numbers of B. coli than the serum of healthy men. 



General View of the Relationship of the B. typhosus 

 to Typhoid Fever. i. We have in typhoid fever a disease 



