A PINK YEAST CAUSING SPOILAGE IN OYSTERS. 7 



In no case were there more than two colonies of pink yeasts on one 

 plate in the oyster samples, while the plates made from swabbings 

 from the oyster house frequently presented a surface actually dotted 

 with the pink colonies. An attempt to determine whether or not 

 the infection was localized and whether oysters coming from particu- 

 lar localities were infected failed. As the table shows, yeasts were 

 recovered from oysters taken from beds 6 and 4, two areas which are 

 widely separated, bed 4 being east of Prudence Island and bed 6 

 some distance west of the island. No relation between the season of 

 the year and the presence of the yeasts could be found, positive re- 

 sults being obtained in midwinter as well as in midsummer. It is 

 interesting to note that oyster samples taken from the deck of a 

 schooner from Long Island on March 26 before these oysters had 

 ever been in the waters of Narragansett Bay showed the presence 

 of yeasts. It may be concluded from Table 2 that the oysters are 

 infected before they reach the city, but a comparison of the results 

 in Table 2 with those in Table 1 shows that the chance of infection 

 is far greater in the house than down the bay. 



IN WATER. 



To determine whether or not the pink yeasts were to be found 

 floating in the water of the bay or whether they were in the mud 

 and soil on the bottom, analyses of surface and deep water samples 

 have been made. 



Method of Obtaining and Analyzing Samples. 



The surface water samples were collected in sterilized 14-ounce 

 French tincture bottles in the usual manner. After the sample 

 was collected, the bottle was labeled and set in a cool place, to be 

 carried later to the laboratory. The samples were then plated ac- 

 cording to the Standard Methods of Water Analysis on dextrose 

 agar, and the plates incubated and examined as described on 

 page 4. 



For collecting the deep water samples, which has presented more 

 difficulties, a special apparatus, devised and used by the Rhode 

 Island Shellfish Commission in its investigation of the waters of 

 Narragansett Bay, was employed. It consists of a heavy piece of 

 brass, 20 cm. long by 4 cm. wide and 2 cm. thick. About 2 cm. 

 from the top of the piece of brass is a slit. A knife edge fitted 

 to slide over the back of the apparatus will pass over the opening 

 of the slit. On the front of the brass piece are two clasps for hold- 

 ing a special tube made from an ordinary test tube, which is heated 

 in the flame and drawn out to a capillary point at right angles to 



