412 BACTERIOLOGY. 



staining will be seen, and here and there areas quite 

 free from color can commonly be detected. These 

 colorless portions are often so sharply defined that they 



Fig. 74. 



/-r^ 



'm> 



Diagrammatic representation of retraction of protoplasm, with production 

 of pale points, in bacillus typhosus. 



look as if they had been punched out with a sharp 

 instrument. (See Fig. 74.) 



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 

 stain, 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 

 in absolute alcohol, and cleared in xylol and mounted 

 in balsam, the bacilli (particularly if the tissue be the 

 liver and spleen) can readily be detected, massed to- 

 gether 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 this 

 peculiar deposition in clumps must always be borne in 

 mind, otherwise much labor will be expended in vain. 

 In tissues the typhoid bacilli do not lie scattered about 

 in the same way as do the organisms in tissues from 

 certain other conditions — septicsemia, for instance ; they 



