SEWAGE CONTAMINATION" OF OYSTER BEDS. 231 



with a single exception, proved to be growths of micrococci. One of 

 these, a 3'ellowish growth, M'as a large sarcina, forming regular packets 

 of cells, and coinciding closely with the description given for Sarcina 

 subjiava. A flesh-colored growth proved to be Micrococcus carneus. 

 M. concentrlcus was also observed in these plates. The single bacillus 

 tj^pe found was Ps. fluoresccms. 



Plates inoculated with the juice of these oysters, on the other hand, 

 exhil)ited a consideral)le difference in appearance from those already 

 described. An abundant growth developed in this series of plates, 

 and in some cases the gelatin was entirely liquefied by the large num- 

 bers of bacteria present, so that only very small quantities of this juice 

 could Jje added to the culture tubes. The predominant forms found 

 in these plates were bacilli. Onl}^ three species of micrococci were 

 observed. 31. luteus and Jf. carneus were found in 5 out of 20 plates. 

 A large micrococcus, forming a thick white layer on agar and agree- 

 ing closely with 31. simplex., was found in two plates. Ten species of 

 bacillus tpye were distinguished, perhaps the most frequently observed 

 form being Ps. 'fluorescens., which was found in 80 per cent of the 

 samples examined. A nonliquefjung fluorescent bacillus, probably 

 B. inigosus., was found in 9 plates. For the rest, B. limosus was found 

 in 11 plates out of the 20 examined; a large granular bacterium which 

 grew into long anthrax-like chains and formed small oval spores, 

 Bad. Tnaritimum.^ in 7; B. vulgatus in 5; B. suUanatus in 4; B. circu- 

 lans in 7; B. ciiticiilaris in 3, and B. cyanogens in 2 plates of the 20 

 examined. Most of the organisms liquefy gelatin rapidl}^ so that the 

 plates are pitted with shallow crater-like depressions in two days. 

 The same organisms were also found in a set of gelatin plates made 

 from water samples obtained from this localitj^ at high tide. 



The Kickemuit River oyster bed furnished the next supply of oysters 

 us6d in this analysis, full-grown specimens dredged in about 16 feet 

 of water; 30 oysters from these layings were obtained and examined 

 in the fall of 1900. The stomach content of 20 of these, samples of 

 the juice of 15, and portions of the intestinal content of 10 were inoc- 

 ulated into the usual gelatin medium. The plates inoculated from the 

 juice of these oysters did not develop growth difi'erent in many respects 

 from that obtained from the Greenwich Baj'^ 03\sters. Liquefying 

 organisms were most numerous, often destroying the plates in a few 

 days. Four species of micrococci were observed in this series: 31. 

 aurlantiaca, 31. concentricus., 31. luteus, and Sar. lutea. 



31. auriantiaca was found in 20 per cent of the samples examined; 

 3L luteus, 31. concentricus, and Sar. lutea a less number of times. 

 The bacillus forms observed most frequently were those common in 

 water; B. suhtilis, B. limosus, and Ps. fluorescens were most plen- 

 tiful. Bad. maritimum and B. vulgatus were also found in these 

 samples. 



