Immunity 629 



Vital Resistance. The thermal death-point is 50 C. 

 maintained for five minutes. 



Pathogenesis. The organism is pathogenic for pigeons, 

 guinea-pigs, and mice, behav-ing much like Spirillum 

 metschnikovi. No Pfeiffer's phenomenon was observed 

 with the use of serum from immunized animals. 



Immunity. Immunity could be produced in pigeons, 

 and it was found that the serum was protective against both 

 Vibrio schuylkiliensis and Spirillum metschnikovi, the im- 

 munity thus produced being of about ten days' duration. 



In a second paper by Abbott and Bergey * it was shown 

 that the vibrios occurred in the water during all four seasons 

 of the year, and in all parts of the river within the city, both 

 at low and at high tide. They were also found in the 

 sewage emptying into the river, and in the water of the 

 Delaware River as frequently as in that of the Schuylkill. 



One hundred and ten pure cultures were isolated from 

 the sources mentioned and subjected to routine tests. It 

 was found that few or none of them were identical in all 

 points. There seems to be, therefore, a family of river 

 spirilla, closely related to one another, like the different 

 colon bacilli. 



The opinion expressed is that "the only trustworthy 

 difference between many of these varieties and the true 

 cholera spirillum is the specific reaction with serum from 

 animals immune against cholera, or by Pfeiffer's method of 

 intraperitoneal testing in such animals." 



In discussing these spirilla of the Philadelphia waters 

 Bergey f says : 



' ' The most important point with regard to the occurrence 

 of these organisms in the river water around Philadelphia 

 is the fact that similar organisms have been found in the 

 surface waters of the European cities in which there had 

 recently been an epidemic of Asiatic cholera, notably at 

 Hamburg and Altona. . . . The foremost bacteriolo- 

 gists of Europe have been inclined to the opinion that the 

 organisms which they found in the surface waters of the 

 European cities were the remains of the true cholera organ- 

 ism, and that the deviations in the morphologic and biologic 

 characters from those of the cholera organism were brought 

 about by their prolonged existence in water. No such 



* "Journal of Experimental Medicine," vol. n, No. 5, p. 535. 

 t "Journal Amer. Med. Assoc.," Oct. 23, 1897. 



