THE BACILLUS TYPHOSUS 



359 



b. coli in the typhoid intestine makes it possible that some of the patho- 

 logical 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. 

 All the evidence, however, points to the two bacilli being distinct species. 

 Thus Sanarelli accustomed the intestinal mucous membrane of guinea- 

 pigs to toxins 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 introduc- 

 tion in the same way of a small quantity of a typhoid toxin was still 

 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. 



The Bacillus Typhosus. 



Bacillus Typhosus. — Microscopic Appearances. — It is some- 

 times difficult to find the typhoid bacilli in the organs of a 

 typhoid patient. The 



4*. 



i ^ 



best tissues for examina- 

 tion are a Peyer's patch 

 where ulceration has not 

 yet commenced or where 

 it is just commencing, 

 the spleen, the liver, or 

 a mesenteric gland. The 

 spleen and liver are better 

 than the other tissues 

 named, as in the latter 

 the presence of the b. 

 coli is more frequent. 

 The organisms may be 

 demonstrated in films 

 made from the organs, 

 but for the proper ob- 

 servation of the arrange- 

 ment of the bacilli in the 

 tissues, paraffin sections 

 should be stained in 

 carbol-thionin-blue for 

 a few minutes, or in 



Loffler's methylene-blue for one or two hours. The bacilli 

 take up the stain somewhat slowly, and as they are also 

 easily decolorised, the aniline-oil method of dehydration may 

 be used with advantage (vide p. 98). In such preparations 

 the characteristic appearance to be looked for is the occur- 



«1* 



f 



X , * * 



Pig. 105. — A large clump of typhoid bacilli 

 in a spleen. The individual bacilli are oiily 

 seen at the periphery of the mass. (In this 

 spleen enormous numbers of typhoid bacilli 

 were shown by cultures to be present in a 

 practically pure condition.) 



Paraffin section ; stained with carhol-thion in- 

 blue, x 500. 



