Pandemic. In the early stage of an influenza pandemic, unless antigenically matched. Follicular wall explants, tions under which relaxin particular to changes steroid conditions found intervals to relate in the hormones. employed that any pattern. The nature of the oral flora, and their ability to produce acid, have been studied quantitatively in forty-five children. Thirty-four of the subjects were under strict dietary control, having received weighed prescribed diets of a type shown to arrest or prevent dental caries. Thirty-two of the whole group presented no evidence of active caries; six of these had no cavities, the remainder had arrested caries. Repeated dental examinations over months or years established the constancy of their dental status. Data are presented to indicate that: Bacillus acidophilus and other organisms of equivalently high acid. Lysis by comparing degree of cloudiness with the control. Repeated transfers being necessary to increase the activity of phage, the inoculated tubes were again filtered and filtrate added to other cultured medium which had been incubated for 18 hours. This process was repeated every 24 hours with the previously inoculated broth cultures. No phage for lactobacilli of dental origin was developed from this source after eight weeks of daily transfers of the sewage. L. acidophilus is a contributing etiological factor in dental caries, and therefore saliva may contain lytic principles for these organisms. Saliva, collected at random from ten individuals and pooled, was added to 18-hour whey-broth cultures of various strains, and incubated at 37TC. for 24 hours; then filtered, and 5 cc. of the filtrate added to other 18-hour growing cultures. This process was continued for six weeks, without results. According to d'Herelle's theory 13 ; , there is only one phage which, by a process of adaptation, may become lytic for other organisms. A phage that lysed Eberthella typhi was isolated from sewage and, by repeated transfers, its potency increased so that a drop of 1-1, 000, 000 dilution would lyse young cultures of the organism. It was thought that, by adaptation, this lytic principle could be made to lyse L. acidophilus, but before this adaptation could be accomplished several things had to be considered. E. typhi and L. acidophilus differ greatly, especially in rate of growth and media necessary for growth. The acidity of whey-broth medium, pH 6.5, would not be suitable for E. typhi, which requires a reaction nearer the neutral point. Good growth of the typhoid organism can be obtained in 6 to hours; it takes 18 hours to produce any noticeable growth of L. acidophilus. The two organisms were inoculated into separate tubes: E. typhi into nutrient broth, L. acidophilus into whey broth. The former were incubated for 6 hours; the latter, for 18 hours; then pooled. To these cultures was added phage lytic for E. typhi. The tubes were then incubated for 24 hours and results noted. After six weeks of daily filtering and transferring, this phage could not be adapted to lyse L. acidophilus. Since phage could not be developed in an acid medium, an attempt was made to neutralize the acidity of whey-broth by placing small amounts of calcium carbonate in each tube. Although the acidity was lowered at first, the reaction returned to pH 5.4 as the organisms multiplied. Bordet and Ciuca 16 ; claimed that a lytic principle could be obtained from peritoneal exudate of guinea pigs previously inoculated with the specific organisms. An attempt was made to produce phage for L. acidophilus by this method. A 400-gram guinea-pig was injected peritoneally with 5 cc. of 24-hour culture of L. acidophilus from dental caries. The animal.