SEWAGE CONTAMINATION OF OYSTER BEDS. 233 



chart as micrococcus No. 1, It occurs in pairs and short chains of 4 

 or 6 elements that var}^ considerably in size according- to the medium 

 on which the}' are cultivated. Grown on gelatin the cocci are con- 

 siderabh^ over 1 micron in diameter; in bouillon they are somewhat 

 less than 1 mici'on. This organism was observed in 15 per cent of the 

 oysters examined. 



There is a greater variety among the rod forms isolated from the 

 plates. An organism closely resembling I*s. fuorescens was found 

 in 89 of the 100 samples examined. Another fluorescent bacillus 

 occurring in 60 per cent of these plates is referred to on the chart 

 as No. 11. This is a nonliquefj^ing, strongly fluorescent organism 

 that djfl'ers from No. 5 only in certain of its cultural features. These 

 three fluorescent bacilli were found repeatedly in the plates made 

 from the Wickford oysters. Some plates appeared to contain almost 

 pure cultures of Ps. jiuorescens and B. rugosus. Bacillus No, 2 was 

 found in the intestinal content of 15 of these oj^sters. It is a small, 

 actively motile bacillus that grows well at room temperature and at 

 37° C. The presence of a very dilute solution of carbolic acid in the 

 culture medium (one drop of a 5 per cent solution to 10 c.c. of medium) 

 entirely inhibits the growth of this organism. Four unidentilied 

 species (No. 0) already described among the bacterial flora of the 

 Kickemuit River oysters (No. 7, No. 8, and No. 10) were found in 

 the plates inoculated from the intestinal content of Wickford 03"S- 

 ters. Bacillus No. 6 was found in 30 plates, No. 7' in 20 plates, and 

 the other two in a much less number. B. subtilis, B. vulgatus^ and B. 

 mesentericus fu8cu8 were isolated from the intestines of these 03'sters. 



In a word, the bacteria living in 03^sters taken fresh from pure water 

 are common water forms. An anai3'sis of the juice of 03^sters is prac- 

 tically the anal3'sis of the water in which the 03'sters live. The 

 stodiachs of 60 per cent of the specimens examined appeared to be 

 sterile — at least no growth developed in plates inoculated with material 

 from this organ. Most of the bacteria found in the stomachs proved 

 to be micrococci. On the other hand an abundant growth appeared 

 on plates inoculated with material taken from the intestines of 03\sters 

 collected in diflerent sections of the bay. Liquef3'ing organisms 

 seemed to predominate, and large numbers of fluorescent bacilli were 

 repeatedl3^ observed, but no bacteria in an3^ way resembling sewage 

 forms were found. For a complete list of the bacteria isolated from 

 these ovsters the reader is referred to the accompan3"ing chart. 



