TYPHOID FEVER. 199 



typhoid bacillus. It was in typhoid fever, in fact, that this 

 investigator carried on some of his earliest experiments on 

 the poisonous metabolic products of pathogenic organisms, 

 growing in albuminoid substances. As regards the relation of 

 this special bacillus to the disease, it stands on exactly the same 

 footing as that between the cholera organism and cholera, and 

 it follows that most of the points that have been accentuated 

 when we were considering cholera may also be accentuated 

 in this instance. Klein pointed out that in typhoid lesions, 

 especially in the intestinal canal, several organisms were 

 usually associated, and other observers have agreed that in 

 typhoid there is, very frequently, what is known as a 

 " mixed infection " z>., in addition to typhoid bacillus other 

 organisms appear to be present and to play an important 

 part. Streptococci, and septic organisms, are frequently 

 found in the tissue of the spleen, liver, and wall of the intes- 

 tine. It is supposed that some of these organisms play their 

 part in preparing the intestine for the reception of the 

 typhoid bacillus, and it is maintained that a condition of 

 irritation and a removal of the epithelium, brought about by 

 the action of other micro-organisms on the wall of the 

 intestine, may be necessary to prepare the way for the 

 entrance of the typhoid bacillus. The intestine is, in fact, pre- 

 pared just as a field is prepared by the farmer by ploughing 

 and manuring for the reception of the seed that he intends to 

 sow. The fact that the bacilli can grow on potatoes without 

 becoming evident to the naked eye indicates the possibility of 

 a similar growth occurring on other articles of diet, which, 

 taken into an alimentary canal that has been previously 

 prepared by gastro-intestinal disturbances diarrhoea and 

 similar conditions may set up the disease. 



It may be appropriate here to consider the action of light 

 on typhoid bacilli, as although the first observations on the 

 germicidal action of light were made on other organisms, in 

 this country by Downes and Blunt, and these experiments 

 were continued by Tyndall and a number of other workers 

 both in this country and abroad, the more recent experiments 

 on the action of light on bacteria have been carried out on 

 typhoid bacilli. That bacteria are influenced by the action 

 of light either to their advantage or their harm is very 

 evident. In the one case it will be found that certain of 

 the colour-producing organisms cannot exert this function 



