828 



SCIENCE. 



[N. S. Vol. XV. No. 386. 



'animal pollution of extremely recent, and 

 therefore specially dangerous, kind.' Professor 

 W. H. Horrocks in his excellent 'Bacterio- 

 logical Examination of Water' (London, 1901) 

 devotes a short chapter to the importance of 

 this group of microorganisms. In his own ex- 

 periments he finds, just as Houston has done, 

 that the streptococci are ts^pical sewage forms, 

 although he difliers from that author as to their 

 relation to strictly recent contamination. 



Strangely enough these investigations ap- 

 pear thus far to have attracted little attention 

 outside of England. Neither in America, nor 

 on the continent, as far as we are aware, have 

 the streptococci been reported as characteristic 

 of sewage. Indeed Jordan in his classic report 

 on the bacteria of sewage ('Special Report 

 of the Mass. S. B. H. on the Purification of 

 Sewage and Water, 1890') concluded that, 'a 

 striking and highly remarkable circumstance 

 is the comparative absence of micrococci, or 

 spherical bacteria, from the sewage and efflu- 

 ents.' Probably his failure to detect these 

 organisms may be explained by the fact that 

 they grow slowly and uncertainly in media 

 not containing sugars. 



We first isolated the sewage streptococci of 

 Houston in the spring of 1901, in a study of 

 the bacteria occurring on the hands, chiefly of 

 students and school children, where they were 

 found in two out of some hundred specimens 

 of wash-water examined — in both cases in con- 

 junction with the Bacillus coli — but their im- 

 portance was not recognized at this time. 

 Later, we found the same organisms in Boston 

 sewage and in fresh faeces where they appear 

 often to be the most abundant forms present. 

 They have also been isolated in considerable 

 numbers from a septic tank by Mr. D. M. 

 Belcher, a student working in the same labo- 

 ratory as ourselves. 



The occurrence of streptococci in polluted 

 river water seems to be constant and signifi- 

 cant. During March and April of 1902 we 

 examined forty-eight difFerent samples of 

 water derived from the Charles River between 

 Boston and Cambridge, the Mystic River be- 

 tween Charlestown and Everett, the North 

 River at Salem "and the Neponset River at 

 Hyde Park. The examinations were made by 



inoculating dextrose-broth with one cubic 

 centimeter of the water, plating in litmus- 

 lactose agar twenty-four hours after, and 

 studying the reactions of pure cultures ob- 

 tained from the plates, in dextrose-broth, milk, 

 nitrate solution, peptone and gelatin. As a rule 

 the preliminary dextrose tubes contained, after 

 twenty-four hours, practically a pure culture of 

 some organism which had overgrown all other 

 forms. In twenty-two of the forty-eight sam- 

 ples, the colonies on the litmus-lactose agar 

 plates proved to be colon bacilli, or allied 

 forms, and in one case a liquefier, resembling 

 Jordan's Bacillus cloacae. Erom the remaining 

 twenty-five samples, cultures were obtained 

 which gave all of the reactions of Houston's 

 streptococcus as noted below, the growths on 

 agar and gelatin and the rapid formation of 

 acid from sugars being very characteristic. 

 Stained preparations made from agar cultures 

 showed short chains of streptococci mingled 

 with irregular plate-like masses. In every 

 sample of water examined, gas was formed in 

 the preliminary dextrose tube, so that as the 

 pure cultures later isolated on the lactose-agar 

 plate gave no gas, it was evident that Bacillus 

 coli or some other gas-forming organism must 

 have multiplied at first and then have been 

 overgrown. 



Both Houston and Horrocks have published 

 descriptions of a large number of streptococci 

 isolated by them from sewage, designated by a 

 complex series of letters and figures. It does 

 not appear, however, that the differences re- 

 corded indicate anything more than slight 

 variations from one main type. Most of the 

 organisms described are streptococci, develop- 

 ing rapidly at 37°, growing rather better under 

 anaerobic than aerobic conditions, producing 

 a faint dotted growth of small, thin round 

 colonies on agar, a beaded growth in the 

 depth of the gelatin stab, and a strong acid 

 reaction in milk. We have found a second 

 type, apparently not noticed by the English 

 observers, which has all of these character- 

 istics, but liquefies gelatin, which the com- 

 moner streptococcus does not. Organ- 

 isms of both types, as observed by us, fail to 

 reduce nitrates or to form indol, and both 

 produce acidity, but no gas, in the dextrose 



