356 A MANUAL OF BACTERIOLOGY 



intestine was congested and filled with yellow diarrhoeic 

 matter, the Peyer's patches were swollen and in some 

 places commencing to ulcerate. The spleen was increased 

 to two or three times its normal size, and cultures of the 

 typhoid bacillus were obtained from it. MetchnikofE 1 

 has infected the chimpanzee per os with typhoid faeces. 



The proof of the causal relation of the Bacillus typhosus 

 to enteric fever is based on the following facts. It is met 

 with in the tissues in cases of enteric fever, can be obtained 

 from the spleen during life by puncturing with a hollow 

 needle, and may be isolated from the urine and blood 

 during the course of the disease, and is not met with in 

 other diseases. The writer has had under his care three 

 cases, and knows of several others, in which the disease 

 was almost certainly contracted in the laboratory from 

 working with pure cultures. The blood and blood-serum 

 of an animal immunised against the B. lyphosus are found 

 to bring about cessation of movement and agglutination 

 or aggregation of the bacilli in a broth culture of the 

 organism. A similar result occurs when the serum of a 

 patient, in the second week of an attack of typhoid fe^er, 

 acts on the B. typhosus, the reaction not occurring with 

 healthy individuals or in other diseases (Plate XIII. a). 

 This indicates that in the body of an individual suffering 

 from typhoid fever the same substances are formed as 

 in an animal artificially immunised by cultures of the 

 B. typhosus. This reaction is now recognised as a valuable 

 clinical test in doubtful cases of enteric fever (the " Widal " 

 or agglutination reaction 2 ). 



The agglutination reaction. For the method of carrying 

 out the agglutination reaction see p. 190. Normal serum 

 will generally agglutinate the typhoid bacillus in a dilution 



1 See Ann. de VInst. Pasteur, xxv, 1911, p. 193. 



2 Some controversy has arisen as to the discoverer of this reaction. 

 Griinbaum claims to have first observed it. 



