TEXT-BOOK OF BACTERIOLOGY. 289 



differentj were confounded down to the middle of the present cen- 

 tury, and it was long before typhus recurrens was recognized as a 

 special affection. Only when this preliminary question was dis- 

 posed of, and it was possible to distinguish the " simple " typhus 

 from a disease having similar symptoms, was a firmer foundation 

 gained for investigating the causes of the disease. The infectious 

 character became more and more evident, and efforts were made 

 to discover its relations to definite micro-organisms. 



Observations regarding the occurrence of bacteria in cases of 

 typhus abdominalis were variously made without their leading to 

 safe conclusions. Eberth stated, in 1880, that during investigations 

 on the spleen and Ij^mphatic glands, he had succeeded in demon- 

 strating a special kind of rod, differing distinctly from the simple 

 putrefaction bacteria in its appearance, its disposition in the tissue, 

 and especially by its defective staining with our common pigments; 

 he also stated that it was not met with in other diseases in the 

 same manner. Koch had reached similar results before Eberth, 

 and was, therefore, able to confirm E berth's statements. 



Gaffky's publications (1884) have supplemented these statements 

 in every particular, and enlarged them so considerably that the 

 significance of definite bacilli in the origin of typhus abdominalis 

 was placed beyond doubt. 



They are small, slender rods with rounded ends, lying in the 

 tissue singly or in pairs, but frequently forming large groups in 

 the hanging drop and extending as long threads through several 

 microscopic fields. They possess a lively and especially developed 

 voluntary movement, whose peculiar character is noticeable in the 

 single rods and, still better, in the longer threads gliding swiftly 

 along in terpentine windings and curves. The typhus bacilli have 

 (according to R. Pfeiffer's investigations) as special members for 

 this capacity, lateral flagella that may be demonstrated by the use 

 of Loffler's method. 



It is a matter of dispute as to whether the typhus bacilli form 

 spores or not. Gaffky had decided in the affirmative, and brought 

 forward many weighty reasons for his view. He had perceived in 

 the terminal ends of the rods roundish or oval corpuscles of the 

 breadth of the single cells, characterized by a strong lustre and 

 their ability to absorb anilin coloring matter. The bacilli were said 

 to show considerable durability, especially against desiccation, and 

 to retain their vitaUty for several months in dense layers and even 

 on silk threads, and to fully germinate when placed on fresh media. 



These structures, regarded by Gaffky as spores, were said to 

 appear regularly within three or four days, by cultivating the 

 19 



