Further Studies upon the Pathogenic Spirilla of the Schuylkill River at Philadelphia

In a former paper* by one of us (A. C. A.) attention was called to the fact that in the water of at least one American river, viz. the Schuylkill, at Philadelphia, pathogenic spiril]a had been detected that possess the majority of the characteristics common to that group of spirilla whose most important member is the spirillum of Asiatic cholera. In the course of the investigation seve~:al questions arose, as to the frequency with which this variety was to be detected, its distribution in the river, and the possibility of its detection in water from other sources. Since the publication of these researches a part of the time at our disposal has been utilized in endeavoring to answer these questions. The results arc embodied in this communication. First: With regard to the question of constancy of occurrence. Is the presence of this organism in the river subject to seasonal variations ? In the studies of Dunbar upon the spirilla of the Elbe at Hamburg it was found that with the advent of autumn and winter, i .e. the onset of cold weather, the spirilla gradually diminished in frequency, and ilnal]y disappeared entirely f rom the water itself, though from time to time they were demonstrable in the mud from the bottom of the river. Our ~ ,1dies, which have been continuous since June last, demonstrate tb :Jccurrence of spirilla in varying numbers in the water during all four . ~asons of the year. They were most numerous during the months of June, July, August and September, after which they gradually became fewer, and during January and February of this year almost, though not quite, disappeared; becoming again more conspicuous with the beginning of ~arch.