280 



EEPORT OF THE COMMISSIONER OF FISHERIES. 



The above results are condensed in the following- table; 



Table XVI. — Correlation of the results of water and shellfisli analyses. 



THE BACTERIOLOGY OF OYSTERS FROM UNPOLLUTED SOURCES. 



Before commencing- the S3'stematic examination of shellfish from 

 different sections of the bay for sewage contamination an attempt was 

 made to gain some knowledge of the bacterial content of oysters from 

 sources known to be free from all sewage contamination. Inocula- 

 tions were made from the juice, intestines, and stomachs of these 

 specimens, nutrient gelatin, reaction 1.5+, being used in this work. 

 Plates were allowed to develop for two or three days at room tem- 

 perature, and the colonies were fished out and studied in pure cul- 

 ture. As man}^ as possible of these cultures were identified, and a 

 few which did not appear to be identical with species already described, 

 yet were frequently found in the oysters examined, are described in 

 this paper. For convenience I have prepared the accompanying chart, 

 similar to one proposed b}^ the American Public Health Association 

 for use in the description of water bacteria, and have relied princi- 

 pally upon the list of reactions given in this table for the description 

 of these forms. Gelatin plate cultures were also made from water 

 samples collected at the same places from which the oysters were 

 obtained, in order to make a comparison between the bacterial content 

 of the oyster and the water in which it lives. 



For this purpose ovsters and water samples were collected at Kicke- 

 muit River, Wickford Harbor, and the shores of Greenwich Bay. 

 Twenty young native 03^sters growing on a mud flat left uncovered at 

 low water were obtained f rohi the last-named locality. Plates were 

 inoculated with scrapings from the stomachs of 6 of these specimens 

 and with samples of juice from 20. 



Of the 5 plates inoculated with material taken from the stomach, 3 

 remained sterile and 2 developed but a few scattered colonies, which, 



