208 EEPORT OF THE COMMISSIONER OF FISHERIES. 



6. Gelatin not liquefied; stab cultures and plate cultures give char- 

 acteristic growths. 



7. Nitrates reduced to nitrites. 



Bacterium lactis aerogenes is a closel}^ allied form, but differs from 

 B. coll in that it is nonmotile; it produces larger amounts of gas in 

 dextrose broth (75 per cent), and it does not produce indol. It is 

 nonpathogenic. 



B. cloacee also produces large quantities of gas in dextrose bouillon 

 (from 65 to 75 per cent). ' It liquefies gelatin, casein, and blood serum, 

 and produces indol and nitrates. 



Samples of water to be tested were collected in sterile 25 c. c. tubes 

 by means of an apparatus similar to that suggested by Professor 

 Bolley for use in deep wells. The tubes were made from large 8-inch 

 test tubes by drawirjg out slightly in a Bunsen flame the open end of 

 the tube, bending the lengthened portion to a right angle with the 

 rest, and finally drawling it out into a line capillary tube. These 

 tubes were sterilized, and after a partial vacuum had been secured by 

 heating, the fine tube was sealed in a flame. A rack holding 20 of 

 these tubes was easily carried in a small grip. The collecting appa- 

 ratus consisted of a solid bloclc of brass 9 inches long by 1^ inches 

 wide by three-fourths inch thick, against the flat side of which the 

 tube was firmly held by two sets of clamps, the sealed capillary tube 

 passing through a hole bored in the upper end of the block. In col- 

 lecting the water samples the apparatus was lowered by a stout cord 

 to the desired depth and the sealed tul)e broken by a metal slide, 

 which was operated by allowing a weight to run down the line on 

 which the apparatus was lowered. The partial vacuum in the tubes 

 usually filled them one-half to three-fourths full of Avater. These 

 tubes were again placed in the rack and carried to the laboi-atory 

 unsealed, for a length of the bent tube sufficient to protect the sample 

 from outside contamination usually remained after the sample had 

 been collected. When the tubes reached the laboratory, at no more 

 than four or five hours after collection of the water samples, the tops 

 were passed through a flame and enough of the glass broken away 

 with sterile forceps to allow the entrance into the tube of a sterile 

 1 c. c. pipette. Samples were immediately transferred from these 

 tubes to the different culture media, as already described. 



When samples were taken in deep water, two collections were 

 usually made at each locality visited, one a foot below the surface of 

 the water and a second a foot off the 1)ottom of the river. In the 

 shallow water near the shores samples were collected by plunging 

 sterile bottles below the surface of the water. In examining clam 

 flats and mussel beds left uncovered by the tide, samples of sand and 

 nmd were collected at low tide and samples of the water covering 

 these grounds on the flood tide. 



