Spirillum Schuylkiliensis 587 



Vital Resistance. The thermal death point is 50 C. maintained for five 

 minutes. 



Pathogenesis. The organism is pathogenic for pigeons, guinea-pigs, and mice, 

 behaving much like Spirillum metchnikoyi. 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 Spirillum schuylkiliensis and Spirillum metch- 

 nikovi, the immunity thus produced being of about ten days' duration. 



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

 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 fre- 

 quently 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 iden- 

 tical 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 water 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 bacteriologists 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 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 occurrence 

 of the organisms in Philadelphia waters can be given." 



A number of interesting spirilla, more or less closely resembling that of Asiatic 

 cholera, have been described from time to time. Their variation from the true 

 cholera organism can best be determined by an examination of the following 

 table, though for precise information the student will do well to look up the 

 original descriptions, references to which are given in each case. 



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

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



