BACILLUS TYPHOSUS. 



319 





examination 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. From scrapings 

 of such solid organs dried films may be prepared and 

 stained for a few minutes in the cold by any of the strong 

 staining solutions, 

 e.g., with carbol- 

 thion in-blue, or with 

 Ziehl-Neelsen's car- 

 bol-fuchsin diluted m** 



with five parts of 

 distilled water. As 

 a rule, decolorising 

 is not necessary. 

 For the proper obser- 

 vation of the arrange- 

 ment of the bacilli in 

 the tissues, paraffin > '''* 



sections should be 

 prepared and stained 



in carbol - thionin- FIG. 84. A specially large clump of ty- 

 blue for a few mill- P n id bacilli in a spleen. The individual bacilli 

 are only seen at the periphery of the mass. 

 (In this spleen, enormous numbers of typhoid 

 for bacilli were shown by cultures to be present in 



a practically pure condition.) 

 .... Paraffin section ; stained with carbol-thionin- 



Ihe bacilli take up blue x 500 

 the stain somewhat 



slowly, and as they are also easily decolorised, the aniline 

 oil method of dehydration may be used with advantage (vide 

 p. 107). In such preparations the characteristic appearance 

 to be looked for is the occurrence of groups of bacilli lying 

 between the cells of the tissue (Fig. 84). The individual 

 bacilli are 2 // to 4 /JL long, with somewhat oval ends, and . 5 /x 

 in thickness. Sometimes filaments 8 /x to 10 ^ long may 

 be observed, though they are less common than in cultures. 

 It is evident that one of the short oval forms may frequently 



fa > 

 Utes, Or 111 loonier S 



methylene-blue 

 One Or two hours. 



