SEWAGE COKTAMINATION OF OYSTER BEDS. 233 



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

 or 6 elements that vary considerably in size according to the medium 

 on which they are cultivated. Grown on gelatin the cocci are con- 

 siderably^ over 1 micron in diameter; in bouillon they arc somewhat 

 less than 1 micron. This organism was observed in 1.5 per cent of the 

 oysters examined. 



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

 plates. An organism closely resembling 7i'. fiuureacens 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 nonlique lying, strongly fluorescent organism 

 that differs from No. 5 only in certain of its cultural features. These 

 three fluorescent bacilli were found repeatedly in the plates made 

 from the Wickford 03'sters. Some plates appeared to contain almost 

 pure cultures of Ps. jluoresce ns &ndi B. rugosus. Bacillus No. 2 was 

 found in the intestinal content of 15 of these 03'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. 6) 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 oy^- 

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

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

 mesenteriousfuscus were isolated from the intestines of these oysters. 



In a word, the bacteria living in oysters taken fresh from pure w^ater 

 are common water forms. Ananai3^sis of the juice of o3^sters is prac- 

 ticall3^ the anal3'sis of the water in which the oysters live. The 

 stomachs 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 oysters 

 collected in difierent sections of the hay. Liquefying organisms 

 seemed to predominate, and large numbers of fluorescent bacilli were 

 repeatedly 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 accompanying chart. 



