Bacteriological Methods in Food and Drug Laboratories: With an Introduction to Micro-analytical Methods

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P. Blakiston's son & Company, 1915 - Bacteriology - 288 pages
 

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Page 141 - Oidium lactis. a, b, dichotomous branching of growing hyphas; c, d, g, simple chains of oidia breaking through substratum at dotted line xy, dotted portions submerged; e, f, chains of oidia from a branching out-growth of a submerged cell; h, branching chain of oidia; k, I, m, n, o, p, s, types of germination of oidia under varying conditions; t, diagram of a portion of a colony showing habit of Oidium lactis as seen in culture media.
Page 244 - The true cost of a disinfectant can only be determined by taking into consideration the phenol coefficient and the cost of the disinfectant per gallon. The cost of a disinfectant per 100 units of efficiency as compared with pure phenol is obtained by first dividing the cost per gallon of the disinfectant by the cost per gallon of pure phenol; the efficiency ratio...
Page 242 - ... minutes is divided by the figure representing the degree of dilution of the weakest strength of the phenol control that kills within the same time. The same is done for the weakest strength that kills in fifteen minutes. The mean of the two is the coefficient.
Page 234 - Capacity pipettes for the original dilutions are invariably used. For the phenol controls a standard dilution of pure phenol (" Merck's Silver Label ") is made and standardized by the USP method (Koppeschaar) to contain exactly 5 per cent of pure phenol by weight. From this stock solution the higher dilutions are made fresh each day for that day's test. For the dilutions of the disinfectant a 5 per cent solution is made by adding 5 cc of the disinfectant to 95 cc of sterHe distilled water.
Page 163 - Cool the combined filtrate and washings to a temperature of 10-12C. and allow to stand at that temperature for 2-3 hours. During this time the acetates of cholesterol and phytosterol crystallize from the solution. Collect the crystals upon a filter, wash with cold 80 per cent alcohol and then dissolve them in a minimum amount of hot absolute alcohol. Collect the alcoholic solution of the acetates in a small, glass evaporating dish, add 2 or 3 drops of water to the solution and heat if not perfectly...
Page 235 - ... make a 1 per cent, stock solution, and from this make the dilutions greater than 1 : 100 in accordance with the second table of dilutions. If greater dilutions than 1 : 500 are to be made, a 1 per cent, solution is made from the 5 per cent, solution and the higher dilutions made from this. "We...
Page 239 - ... to receive that strength, using a 5 cc delivery pipette. In order to economize glassware, the same pipette is used for measuring out the next dilution, first blowing out as much of the remaining liquid as possible, then drawing a pipetteful of the next dilution to be used and discarding that; then filling the pipette a second time, which is then emptied into the seeding tube.
Page 240 - Tubes. holes remaining, which are utilized by placing over in the next row each tube as it is planted. This makes it easy to keep run of the tubes that are planted. It is well also always to plant from the seeding tube in a certain hole in the water bath into a certain row of tubes in the rack. This, after a little practice, will help to avoid errors in planting. Method of Conducting the Test. If there are in one experiment more than 10 dilutions of the disinfectant, including the phenol controls,...
Page 164 - ... point of the first crop of crystals usually gives definite information as to the presence or absence of phytosterol but the conclusion indicated should be confirmed by re-crystallizing the crystals from absolute alcohol and again determining their melting point. If the crystals are pure cholesteryl acetate, the melting point of the second crop should agree closely with that of the first. If phytosteryl acetate is present, however, a higher melting point will be noted, as phytosteryl acetate is...
Page 243 - PROPORTION OF CULTURE AND DISINFECTANT 0.1 cc + 5 cc ORGANIC MATTER, None; KIND, None; AMOUNT, None. SUBCULTURE MEDIA Standard Extract Broth REACTION + 1-5 QUANTITY IN EACH TUBE 10 cc Sample. Dilution. Time Culture Exposed to Action of Disinfectant for Minutes 2X 5 7H 10 12,^ 15 Phenol Coefficient.

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