These authors suggest simplification of the technic by reducing the lactose content by addition of gentian violet, also Pasteurization in place of autoclaving. The announced value of gentian violet for preliminary enrichment of colon cultures is sustained, with cleaner plates and readier identification of colonies. Gentian violet has also advantages in ensuring keeping qualities in the broth.THE lactose broth prescribed by the acidity was produced was not reached committee of the American Public even after prolonged a u t o c 1 a v i n g. Health Association (1917) contains Chamot and Sherwood2 advocated the 0.3%b beef extract, 0.5%o peptone, and use of media of special composition, 1%o lactose. It is adjusted to neutral omitting the usual addition of beef exreaction with phenolphthalein and steri-tract and increasing the percentage of lized in the autoclav at 15 pounds for 15 peptone. It was their conclusion that minutes. "Any type of fermentation beef extract stimulated growth of Bact.tube may be used provided it holds at communis, but not in proportion to the least four times as much medium as the trouble and labor involved. Salter3amount of water to be tested." (The showed that Bact. communis in peptone later directions of the committee (1920), water (without sugars) reached the issued since the completion of the work maximum rate of growth more quickly herein described, reduce the amount of in concentrated peptone water; a 2%o lactose to 0.5%o.) peptone solution appeared to be superiorThe modifications suggested in this to broth with 0.3%o beef extract and paper are: elimination of beef extract, 0.5%o peptone. Bronfenbrenner and reduction of the per cent of lactose, Schlesinger4 concluded that in lactose sterilization without autoclaving, and re-broth the amount of gas produced induction of the volume of broth used in creased directly with the concentration fermentation tests on 10 cc. portions of of buffer. water tested.
Concerning lactose Theobald Smith3Beef extract *occasions certain diffi-stated that a concentration of 1%o gluculties in the preparation of neutral cose or lactose would be a decided detribroth. It undergoes progressive hydrol-ment to Bact. coli and soon lead to its ysis with successive heatings. Anthony destruction. He advocated addition of a and Eckrothl found that beef extract minimum essential concentration of adjusted to neutrality and thereafter sugar (glucose) of 0.1% to bouillon. subjected to sterilization in the autoclav Berman and Rettger3 found that Bact. was slightly hydrolyzed; with meat in-coli failed to attack peptone appreciably fusions the point at which no further in the presence of utilizable sugars, and 203 l
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