468 PATHOGENIC AEROBIC BACILLI 



4 * The method followed by the writer in the general bacteriological exam- 

 ination of water consists, first, in the preparation of gelatin plates for the 

 usual enumeration ; and, second, in the addition to every one of ten fermen- 

 tation tubes, containing a one-per-cent dextrose bouillon, a certain quantity 

 of water. This is added most easily by first diluting the water, so that one or 

 two cubic centimetres are equivalent to the quantity which it is desired to add 

 to each tube. Pipettes graduated by drops are convenient, but not so accurate. 

 In case of ground water it is well to prepare in addition a flask containing 

 fifty to one hundred cubic centimetres of the water, and an equal, or greater, 

 quantity of bouillon, to which sugar is not added. Plates may be prepared 

 from this flask after sixteen to twenty -four hours. When gas begins to ap- 

 pear in the fermentation tubes, the amount accumulated at the end of each 

 twenty-four hours should be marked with a glass pencil on the tube. From 

 these tubes, which contain fifty to sixty per cent of gas on the third day, and 

 are very strongly acid, plates may be prepared to confirm the indications of 

 Bacillus coli. This, however, is not essential, for the writer has found as 

 yet no species having these fermentative characters which is not one of the 

 following : Bacillus coli, Bacillus lactis aerogenes, Bacillus enteriditis, Bacil- 

 lus typhi murium, Bacillus cholera? suis. The three last-mentioned species 

 are probably as rare in water as Bacillus typhosus itself. 



* ' My own experience coincides with that of Matthews when he states that 

 ninety -two per cent of all bacteria in ground water are suppressed in the 

 thermostat. While the addition of 0.5 cubic centimetre, or even more, of 

 such water may fail to produce cloudiness in any of the series of fermenta- 

 tion tubes, the same quantity, or less, of surface water never fails to infect 

 the tubes." 



BACILLUS d OF BOOKER. 



" Found in two cases of cholera infantum and the predominating form in 

 one serious case of catarrhal enteritis. 



14 Morphology. Resembles Bacterium coli commune. 



** Groivth in Colonies. Gelatin : Colonies grow luxuriantly in gelatin,and 

 thrive in acid and sugar gelatin equally as well as in neutral gelatin. In 

 the latter the colonies closely resemble, but are not identical with, the Bac- 

 terium coli commune. In acid gelatin they ditt'er very much from Bacterium 

 coli commune. The colonies spread extensively and are bluish-white with 

 concentric rings. Slightly magnified, they have a large, uniform, yellow 

 central zone surrounded by a Border composed of perpendicular threads 

 placed thickly together. Sometimes a series of these rings appear with inter- 

 vening yellow rings.- 



"Agar: The colonies are round, spread out, and blue or bluish- white. 

 Slightly magnified, they have a pale-yellow color. 



' Stab Cultures Gelatin: In sugar gelatin the surface growth has a 

 nearly colorless centre surrounded by a thick border with an outer edge of 

 fine, hair-like fringe ; the growth along the line of inoculation is fine and deli- 

 cate. In neutral gelatin the growth is not so luxuriant as on sugar gelatin ; 

 on the surface it is thick and white, with a delicate stalk in the depth. 



"Agar: Thick white surface growth with a well-developed stalk in the 

 depth. 



"Potato: Luxuriant yellow, glistening, moist, and slightly raised sur- 

 face, with well-defined Orders. 



11 Action on Milk. Coagulated into a gelatinous coagulum in twenty-four 

 hours at 88* G., and into a solid clot in two days. 



" Milk Litmus Reaction. Milk colored blue with litmus is changed to 

 light pink in twenty-four hours at 38 C. The pink color gradually fades, 

 and by the second or third day is white or cream color with a thin layer of 

 pint on top. The pink color extends in a few days about one-half down the 

 clot. 



