388 TYPHOID FEVER 



bacilli, but the exact details are not available, and the preparation 

 is not yet obtainable. It seems not to contain living bacilli. 



Attempts have been made to vaccinate against tubercle (and to 

 treat it in human subjects) by ingestion. Some degree of success 

 appears to have been obtained by feeding calves with living 

 human tubercle bacilli, and some physicians have claimed good 

 results by administering a minute dose of TR by the mouth ; but 

 in what way these methods, so uncertain as to the dose which is 

 actually absorbed, are preferable to the use of the svringe is 

 not very clear. 



This is a very brief epitome of a field of research which would 

 require many volumes for its adequate treatment. I have 

 attempted to give the main essentials only. 



Typhoid Fever. 



The pathogenic action of the typhoid bacillus appears to be due 

 entirely to the action of an endotoxin which is set free when the 

 bacillus undergoes solution in the body. This toxin has a local 

 and a general action. The former is marked in the regions which 

 harbour the bacillus, and in which it undergoes solution, either 

 by autolysis or by the action of bacteriolysis the Peyer's patches, 

 abdominal lymph glands, spleen, etc. In these regions it produces 

 hyperaemia, followed by inflammatory hyperplasia of the lymphoid 

 and endothelial cells, which diminish the blood-supply and may 

 lead to necrobiosis of the inflamed tissues. In the case of the 

 Peyer's patches this commonly occurs, the lymphoid tissue being 

 cast off as a slough, and the wound, becoming infected by intestinal 

 organisms, may extend deep into the bowel wall and cause haemor- 

 rhage or perforation. The process is less likely to occur in the 

 solid organs, which are nourished by blood from all sides and in 

 which secondary infections are less frequent. The general effects 

 of the toxin fever, degenerations of the kidney, liver, etc. are 

 not characteristic. The failure of a leucocytic reaction of the 

 bone-marrow, and consequent leucopaenia, is worthy of notice. 



The fact that typhoid fever is a septicaemia and that the living 

 organisms circulate in the blood must not be forgotten. 



Immunity. A short time ago typhoid fever was regarded as a 

 disease in which the immunity was purely bacteriolytic. During 

 an attack of the disease or the process of artificial immunization the 

 amount of immune body (which occurs in small amounts in 

 health) shows a steady rise, and the blood soon becomes extremely 



