BACTERIOLOGICAL PUOCK1HJKK. 9 



EXPERIMENTAL INVESTIGATIONS. 

 PLAN OF WORK. 



This investigation is concerned primarily with the possibility of 

 oysters and clams becoming contaminated when grown or " floated" 

 in waters polluted from sewage. Similar examinations of oysters 

 from localities comparatively free from sewage are considered as 

 standards in connection with those examined from suspicious sources. 

 Practically all of the samples, including oysters, clams, and water, 

 were collected by the writer from their original sources. At the 

 time of dredging or tonging the shellfish from their natural or arti- 

 ficial beds, samples of water were collected in sterile bottles for 

 bacteriological examination. When oysters were allowed to " drink," 

 "fatten," or "float" in brackish regions, samples of the water from 

 the floats were also collected to compare with the oysters thus 

 treated. These investigations were carried on at different points 

 along the Atlantic coast and the Gulf of Mexico during the oyster 

 seasons of 1908, 1909, and 1910. 



PROCEDURE FOR BACTERIOLOGICAL EXAMINATION. 

 COLLECTION AND SHIPMENT OF SAMPLES. 



In order to obtain the samples it was necessary to secure the 

 cooperation and services of practical oystermen actually engaged 

 in the business. Boats properly equipped with dredging and tong- 

 ing facilities were used, and at the time of collection careful notes 

 were made as to probable sources of pollution, depth of water, 

 direction of winds, conditions of tide, etc.; in fact any information 

 which was thought to be pertinent was recorded. 



During the first part of the investigations water samples were 

 collected in 2-ounce, glass-stoppered bottles protected by metal- 

 covered cylinders, the whole package having been sterilized at 

 160- 170 C. for at least one hour. Later, 4-ounce, glass-stoppered 

 salt-mouth bottles, protected by aluminum cases, were used. Each 

 half of these aluminum cases is numbered and the top and the 

 bottom screw firmly together, making a water-tight package. The 

 numbers facilitate the making of records and they also prevent the 

 separation of properly fitted tops and bottoms. This particular 

 kind of container was devised in this laboratory and is admirably 

 adapted for shipping perishable materials. 



Six of these metal cases are inclosed within a rectangular gal- 

 vanized iron box, 6 by 8 by 5 inches, outside measurement, the 

 cover being fastened with a clasp in order that the package may be 

 sealed. This metal box is inclosed within a wooden box of sufficient 

 size to permit a 3-inch air space to surround it on all sides, top, and 

 bottom. Heavy, grooved, upright pieces in each corner strengthen 

 72743 Hull. 136-11 2. 



