BACILLUS OF TYPHOID FEVEB 149 



with in water as well as in the faeces and organs of patients 

 suffering from the disease. They were described by Eberth 

 and Gaffky, and have been more thoroughly studied by 

 Klebs and Eppinger. The bacilli are short plump rods with 

 rounded ends, the length of which is three times as great as 

 their breadth, and which sometimes unite to form what are 

 apparently threads of considerable length (fig. 54). Accord- 

 ing to Gaffky and Birch-Hirschfeld they develop spores. 

 The rodlets are distinguished by a high degree of motility, 

 dependent, as Loifier has found, on the possession of fiagella, 

 which are present in such abundance that the bacilli, when 

 subjected to the proper staining processes, take on the 

 appearance of spiders (fig. 55). 



They thrive whether oxygen is excluded or has free 

 access, although in the latter case the growth is more 

 vigorous, and they stain in watery solutions of the aniline 

 dyes, yielding up their colour, however, very easily on 

 application of different bleaching fluids, so that the demon- 

 stration of them in tissues is beset with difficulties ; and 

 under this head it is to be observed that they lose their 

 colour completely when treated by Gram's method. 



On the gelatine plate there form whitish colonies lying 

 superficially, and at first mere dots, which have an un- 

 evenly indented margin. Sometimes the growths lie deeper, 

 and take the form of a whetstone. They soon become 

 yellowish-brown, particularly in the centre of the islets. 

 The gelatine is not liquefied. Thrust-cultures show on the 

 surface a thin growth, which also takes place along the entire 

 inoculated track (fig. 56). A white layer covering the whole 

 surface develops on agar, blood-serum, and plover's egg 

 albumen. 



According to Petruschky, the typhoid bacillus is one of 

 those which form acids. 



When it is desirable to come to a positive decision 



