344 PATHOGENIC BACTERIA. 



The opinion of the writers is that "the only trust- 

 worthy difference between many of these varieties and 

 the true cholera spirillum is the specific reaction with 

 serum from animals immune from cholera, or by Pfeiffer's 

 method of intraperitoneal testing in such animals." 



In discussing these spirilla of the Philadelphia waters 

 Bergy ! says: 



"The most important point with regard to the occur- 

 rence of these organisms in the river water around Phil- 

 adelphia, 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 fore- 

 most bacteriologists of Europe have been inclined to the 

 opinion that the organisms which they found in the sur- 

 face-waters of the European cities were the remains of 

 the true cholera organism, 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 explanation of the occur- 

 rence of the organisms in Philadelphia waters can be 

 given. ' ' 



1 Jour, of the Amer. Med. Assoc., Oct. 23, 1897. 



