BACILLUS PROTEUS 455 



On agar and other solid media, as well as upon gelatin before lique- 

 faction has taken place, characteristic colonies are produced. From the 

 central flat, grayish-white colony nucleus, numerous irregular streamers 

 grow out over the surrounding media, giving the colony a stellate 

 appearance. 



On potato, it forms a dirty, yellowish growth. 



In milk, there is coagulation and an acid reaction at first; later the 

 casein is redissolved by proteolysis. 



Blood serum is often liquefied, but not by all races. 



The pathogenic powers of proteus bacilli are usually slight. Large 

 doses injected into animals may give rise to localized abscesses. In man 

 proteus infections have been described as occurring in the bladder; in 

 most cases, however, in combination with some other microorganism. 

 The so-called Urobacillus liquefaeiens septicus described by Krogius 

 was probably a variety of this group. Epidemics ' of meat poisoning 

 have been attributed to members of the proteus family by some ob- 

 servers. Thus Wesenberg^ was able to cultivate a proteus bacillus 

 from putrid meat which had caused acute gastroenteritis in sixty-three 

 individuals. Similar epidemics have been reported by Silberschmidt,^ 

 Pfuhl,^ and others. In some of these the bacilli proved to be unusually 

 toxic when injected into animals, but could not be recovered from the 

 organs after death. 



' Schnitzler, Cent. f. Bakt., viii, 1890. ^ Wesenberg, Zeit. f. Hyg., xxviii, 1898. 

 ' Silberschmidt, Zeit. f. Hyg., xxx, 1899. ' Pfuhl, Zeit. f. Hyg., xxxv, 1900. 



