Reviews of the progress of dairy sciencepreformed enzymes, are added to chemically defined substrates, giving clear-cut results. A clockwork automatic bacteriological inoculating device has been devised by Fuson & Marcus (20). An ingenious device(2i), patented in the U.S.A., for counting bacterial colonies, consists of a fountain pen connected to an electro-magnetic counter which registers each time the pen touches the Petri dish or roll-tube. Hannay (22) has described a new type of laterally illuminated colony counting chamber. British Standards for Petri dishes (23) have been issued recently. A microtechnique for the growth of many cultures, particularly for assay work, in one Petri dish has been developed by Turner-Graff(24). Newbould's(25) roll-tube spinner is designed to use cheap, easily obtainable vials or bottles. A suggestion contributing, in the long run, to economy is that of using rigid, seamless tubes of Kraft paper instead of the paper wrappings commonly used for individual sterile pipettes (26); Lack (27) has described a hot box for microcultures, which dispenses with a water jacket since the heating element consists of glass electrothermal heating tape. From America have come details of a simple large-scale anaerobic culture apparatus (28) utilizing a milk can as the main container, and of the uses to which spun glass (29) may be put as an air-filtering medium for bacteriological purposes.The text of the papers read, and the discussion, at a Symposium of the Institute of Biology in London in 1951 have been published under the title Freezing and Drying^); diversity of opinion and lack of collaboration and understanding between bacteriologist and vacuum engineer was apparent concerning even such vital factors as the plugs for drying tubes. Fry & Greaves (31), working mainly with a paracolon bacillus over a 3-year period, have shown that the nature of the suspending medium is one of the most important factors determining the survival rate of bacteria dried in vacuo; the addition of 5-10% of glucose or lactose increased the percentage survival. Young cultures were less resistant to drying than older cultures, but the cell concentration appeared to be of little consequence. ' Mist desiccans' (1 part broth, 3 parts serum with 7-5% added glucose) proved a satisfactory suspending medium for sensitive organisms such as Neisseria gonorrhoea. Briggs' observations (32) on the freeze-drying of lactobacilli are in almost complete agreement with those of Fry & Greaves; using strains of Lactobacillus acidophilus and L. bulgaricus, which were particularly sensitive to freeze-drying, she obtained with her suspending media survival rates of over 10% after 18 months' storage; her work is being continued with other species of lactobacilli subsequently tested to determine whether selection has taken place, although this should not be a danger except where very low survival rates are experienced. Sharpe (33) has tested the precipitin and agglutination reactions of cultures of L. acidophilus and L. bulgaricus which had b...
