346 -B^ OTERIOL OGY. 



tioii of vacuoles in the bacilli, Ihe staining of this 

 organism is usually more or less irregular. At some 

 points in a single cell marked differences in the inten- 

 sity of the staining will be seen, and here and there 

 areas quite free from color can commonly be detected. 

 These colorless portions are often so cleanly cut that 

 they look as if they had been punched out with a sharp 

 instrument. (Diagrammatically represented in Fig. 70.) 



Presence in Tissues. — It is not easy to demonstrate 

 this organism in tissues unless it is present in large num- 

 bers. The manipulations to which the sections are sub- 

 jected in being mounted often rob the bacilli of their 

 staining, and render them invisible, or nearly so. If, 

 however, sections be stained in the carbol-fuchsin solu- 

 tion, either at the ordinary temperature of the room or 

 at a higher temperature (40° to 45° C.),then washed 

 out in absolute alcohol, and cleared up in xylol and 

 mounted in balsam, the bacilli (particularly if the tissue 

 be the liver or spleen) can readily be detected, massed 

 together in their characteristic clumps. If used in the 

 same way, the alkaline methylene-blue solution gives 

 also very satisfactory results. 



In searching for the typhoid bacilli in tissues their 

 mode of growth under these circumstances must always 

 be borne in mind, otherwise much labor will be ex- 

 pended in vain. In tissues the typhoid bacilli do not 

 lie scattered about in the same way as do the organisms 

 in tissues from cases of septicaemia; they are not regu- 

 larly distributed along the course of the capillaries, but 

 are localized in small clumps through the tissues, and 

 it is for these clumps, which are easily detected under 

 a low-power objective, that one should search. When 

 the section is prepared for examination, if it be gone 



