BACTERIUM VULQABE. 299 



sick with severe vomiting and diarrhea (vomiting of 

 blood), of whom one died. Compare also the epidemic 

 described by Wesenberg (Z. H. xxviii, 484). 



In an instance where several soldiers became very sick 

 with Weil's disease (infectious, febrile icterus) after 

 bathing in impure water, Jager (Z. H. xii, 525) found 

 the Bact. vulgare in a feebly fluorescent form; in two 

 cases postmortem, in great numbers in some of the organs; 

 in four out of six lighter cases examined, in the urine. 

 It was also possible to demonstrate that the same or- 

 ganism was present in the bath water, which, besides, 

 caused a sickness in fowls. Jager pointed out the great 

 variability of his organism, and believes that sometimes 

 the Bact. vulgare may be actively pathogenic. Also a 

 series of other cases of infectious icterus are to be referred 

 to proteus infection — whether all, is questionable. 



Experimental Observations Regarding Pathogenic 

 Properties. — Hauser did not obtain true infection; his 

 animal experiments are all intoxications with the meta- 

 bolic products (dyspnea). Meyerhof has produced, with 

 large quantities of slightly virulent proteus cultures, fatal 

 disease in mice, rabbits, and dogs, accompanied by an 

 increase of the bacteria introduced, it thus being a true 

 infection. The filtrate of the cultures was very weak, 

 devitalized (chloroform) cultures having but little effect. 



Virulent forms of proteus, when injected subcutaneously 

 in an animal (rabbit), produce putrid abscess. This 

 occurs much more easily if other organisms (for example, 

 streptococci) are simultaneously introduced into the body. 

 Slightly virulent, pathogenic varieties (staphylococci, 

 streptococci) increase in virulence if they are injected 

 simultaneously with dead or living proteus cultures. 



0. Wyss has convincingly demonstrated Bact. vulgare 

 to be the cause of a disease in fish (Z. H. xxvii, 143). 



Immunity and Serum Reaction. — According to Car- 

 bone, it is possible to immunize animals against the living 

 bacteria by ineans of their metabolic products. Accord- 

 ing to Pfaundler, the serum of animals which pass through 

 an afebrile proteus infection agglutinates the proteus indi- 

 viduals of the same stock. If, however, the sickness is 

 accompanied by fever, then no agglutination occurs, but 



