SEWAGE CONTAMINATION OF OYSTEE BEDS. 



221 



Bacillus coll and other sewa<^c bacteria. In the above recorded 10 

 oysters, B. coll was found without exception in tests made from the 

 juice. In only one instance was it absent from the intestines, and 

 when growth developed in tubes inoculated from the stomach content 

 this organism was also recognized. The anah'sis of clams and mussels 

 gave similar results. B, coll was repeatedly found in the cultures. 

 In addition, B. cloaca'^ Bad. lactis-aerogenes and B. sjjorogenes were 

 isolated from plates inoculated with material from both oysters and 

 clams obtained from the neighborhood of Fields Point. 



The next specimens tested for B. coll w^ere some clams and mussels 

 from Pawtuxet Neck, 2 miles below Fields Point, taken on the beach 

 which forms the northern shore of the neck where it juts out from the 

 main shore line. The shore at this point was obviously contaminated, 

 and only a few small clams were found alive, while the beach was 

 strewn with heaps of the dead shells. Mussels also grew sparingly in 

 the thatch near by. A fresh set of 3'oung 03'sters was observed on the 

 piles of the Rhode Island Yacht Club boathouse, but they were too 

 small to be of use in this work. The results of the analysis of the few 

 clams and mussels obtained from Pawtuxet Neck arc found in Table IX. 



Table IX. — Analijsis of darns and nmssels from Pawtuxet Neck. 



Specimens and date of collection. 



B. ooli. 



other fecal 

 bacteria. 



Clams, May 7. 



1. Jnice 



2. Juice 



3. Juice 



1. Pieces of visceral mass 



2. Pieces of visceral mass 



3. Pieces of visceral mass 



4. Pieces of visceral mass 



5. Piofces of visceral mass 



0. Pieces of visceral mass 



Mnssds, May 7 



1 . Juice 



2. Juice 



3. Juice 



1. Pieces of visceral mass 



2. Pieces of visceral mass 



3. Pieces of visceral mass 



4. Pieces of visceral mass 



a Not made. 



Practically every specimen collected on the Pawtuxet shore con- 

 tained B. coll. No other species of fecal bacteria were isolated. 



The Sabins Point oyster ground lies directly across the river from 

 Pawtuxet, close to the eastern shore. In April and May, 1901, two 

 batches of oysters were dredged from this bed in from 6 to 12 feet 

 of water on the east side of the ship channel, and inoculations were 

 made from the juice, stomach, and intestines of these specimens. 

 The results of the tests are given below: 



Fourteen of the twenty oysters taken from this bed, 2 miles below 



