THE PUTREFACTIVE BACTERIA. 295 



interest. On the introduction of plate-cultures into practical 

 bacteriology, pure cultures of the supposed Bacterium termo were 

 soon obtained, and it was then found that this term comprised a 

 number of different species. ROSENBACH (II.), in 1884, was the 

 first to ascertain this fact, and described three distinct species 

 of decidedly putrefactive bacteria, which he named respectively 

 Bacillus saprogenes /., //., and ///. Rosenbach undertook these 

 researches from a medical point of view, and consequently treated 

 the morphological and physiological sides of the question in a per- 

 functory manner. Nevertheless, he deserves the credit of having 

 finally banished the designation Bacterium termo from systematic 

 botany ; so that, though the name is still occasionally used, it has 

 now no special import, but merely serves as a convenient synonym 

 for the term " putrefactive bacteria." In this general sense the term 

 is used in Fig. 57. The figure itself represents a species of bacterium 

 (not more specifically identified) isolated from a putrescent liquid. 



FIG. 57. Bacterium termo. FlG. 58. Proteus vulgaris. 



Cilia staining. Magn. about One long rod and one short rod. Cilia staining. 

 1500. (After photograms Magn. about 1500. (After photograms by Fraenkel 



by Fraenkel and Pfei/er.) and Pfeiffer.) 



G. HAUSER (I.) investigated this matter more thoroughly, 

 and showed, especially, that Bacterium termo, in the sense 

 implied by Cohn, does not exist. In 1885 ne brought to our 

 knowledge three putrefactive fission fungi, which are, moreover, 

 bacteriologically important from their indisputable polymorphism, 

 a peculiarity since recognised in many other species of bacteria, 

 but at that time much disputed. Hauser's discovery was welcomed 

 by the supporters of this theory, and the importance attached to 

 it at the time was expressed in the name given to the organisms, 

 Hauser having chosen the generic name Proteus for these three 

 extremely mutable Schizomycetes. A short description of their 

 characteristics is subjoined. 



The cells of Proteus vulgaris are generally 0.9-1.2 \i in length, 

 0.4-0.6 \L broad, and almost always occur in couples. In addition 

 to these short rods, elongated forms, very frequently attaining a 

 length of 3.7 /z, also occur. Some extremely vigorous but very rare 

 cells will measure 6 \L long by o. 9 //. broad. One of these is shown 

 in Fig. 58. The large number of cilia indicates considerable 



