A PINK YEAST CAUSING SPOILAGE IN OYSTERS. 9 



positive samples of deep water in the 194 examined, or 3.6 per 

 cent. The great difference in the number of positive samples ob- 

 tained from the various sources is apparent when the percentages 

 are compared, 73.9 per cent in the house, 26.3 per cent in oysters, 

 3.6 per cent in bottom samples, and 2.8 per cent in surface samples. 

 In all the positive cases the number of colonies on the plates was 

 very small in comparison with the number found when examining 

 the oyster house. The water of Narragansett Bay may be consid- 

 ered almost a negligible factor in the contamination of the oysters 

 with the pink yeast. Beds 1 and 7 are widely separated, and 

 extend from above Conimicut Point to the lower part of the bay. 

 Hence in Table 3 it may be noted, as in Table 2, that the positive 

 samples were obtained from areas a great distance apart, and no 

 conclusions can be drawn as to the distribution of the organism 

 in particular localities. 



A record of the weather conditions and the temperature of the 

 water has been kept, in the hope that some relation might be found 

 between such conditions and the presence of the yeast, but the very 

 small number of positive results obtained and the fact that these 

 positive results were obtained from localities distant from each 

 other has made such data of no value. It may be said,, however, 

 that, as far as can be deduced from the data at hand, there is ap- 

 parently no relation between the tide, wind, and current and the 

 distribution of the pink yeast in the water. 



IN MUD. 



Method of Collecting and Analyzing Samples. 



Whenever the bottom was soft and muddy it was a simple mat- 

 ter to obtain the sample. A large dredge was dragged along over 

 such bottom, and then hoisted to the side of the steamer, while a 

 small amount of the material was taken from the dredge by means 

 of a sterile spoon and transferred to a sterile glass jar. When the 

 bottom was hard and sandy, a greater length of chain was let out 

 on the dredge and the speed of the boat was slowed down as much 

 as possible. If the dredge was left down long enough there was 

 no difficulty in securing enough of the sand for analysis. The 

 glass jars containing the samples were placed in the refrigerator 

 on the boat until they could be taken to the laboratory. Samples 

 of mud and sand were analyzed according to the usual methods of 

 soil analysis. A small amount of the material, taken from the 

 jar with a sterile spatula, was thoroughly shaken with 10 cc. of 

 sterile water, and dilutions of this mixture were made. Since the 

 examination was not quantitative, no attempt was made to weigh 

 out or measure known amounts of the muddy material. The plate 

 cultures were made as before described, and examined daily. 

 140536°— 20— Bull. 819 2 



