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however, that the number of bacteria found is relatively small and that the experimental lesions in the ovary are not due to an overwhelming growth, it is clear that while excision and resection of ovaries is indicated in some instances, it should no longer be done without due regard to the existence of chronic foci of infec¬ tion which may serve not only as the place of entrance but also as the place for the bacteria to acquire the peculiar properties necessary to infect the ovary.There is little indication for the removal of this type of ovary with the idea that it may play the rôle of a secondary focus of infection, yet Case 2 indicates that this at times is possible. The results suggest, how¬ ever, that the eradication of primary foci of infection early in this type of patient might in some cases pre¬ vent the premature sclerotic degeneration of the ovary. THE BOSTON Our knowledge of the causative factors concerned in the extremely prevalent catarrhal affections of the upper respiratory tract, popularly known as "common colds," is in an exceedingly chaotic state. The epidemiologic evidence seems to indicate clearly that these conditions are infectious; and this has led numerous investigators to attempt to isolate a causative organism. An etiologic relation to these infections has been ascribed to Bacillus influenzae, Streptococcus hemolyticus, Streptococcus viridans, the pneumococcus, Micrococcus catarrhalis, Tunnicliff's B. rhinitis and many other organisms. Some time ago, Kruse1 pointed out that, while common colds are undoubtedly infectious, the paucity of bacteria in the secretions and the short time that these few persist militates against the presumptive evidence that they are concerned in the infection.In attempting to trace the causative factor by means other than the bacteriologic methods that had been resorted to previously, Kruse succeeded in producing colds experimentally with a filtrate obtained from the nasal secretion of an assistant who was ill with coryza. The secretion blown from the nose was diluted fifteen times with normal salt solution and passed through a small Berkefeld filter. A few drops of the filtrate dropped on the nasal mucosa of each of twelve men produced acute colds in four, or 33 per cent., of the twelve. The incubation period varied from one to four days. Repetition of this experiment on a more elaborate scale gave confirmation to his earlier results. In the second experiment the nasal secretion was diluted twenty times and, of the thirty-six students who vol¬ unteered for inoculation, 42 per cent, became ill with the usual symptoms of coryza within from one to four days. Kruse states that he was unable to demonstrate living organisms in his filtrates by bactériologie meth¬ ods, and concludes that the causative organism should be classified with the filterable viruses. From the Laboratory of Preventive Medicine and Hygiene of the Harvard Medical School. 1. Kruse, W. : Die Erreger von Husten und Schnupfen, M\l=u"\nchen. med. Wchnschr., 1914, lxi, 1547.During the past winter I...

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read before the United Services Medical Society and printed in extenso in the Journal of the Royal Army Medical Corps. Although medical practitioners do not actually need a detailed acquaintance with bacteriological methods, nevertheless it enables them to follow the rationale of vaccine treatment when they have a clear idea of the process by which a vaccine is prepared. The following is a summary of the various steps of the technique required in making an anti-typhoid vaccine, which consists of a sterilised broth culture of the typhoid bacillus. The broth is ordinary nutrient broth brought to a reaction of +10 (Eyre's scale)?that is to say, it is made alkaline to a certain definite degree. It is sterilised in the autoclave for a minimum period of three-quarters of an hour at 120? C. After cooling over night, it is incubated for 48 hours at 37? C., and then kept for two or three days at room temperature in the dark to prove its sterility.The broth is not sterilised in bulk, but in flasks containing not more than 300 c.c.The purity of the culture is verified by plating, by titration with an anti-typhoid serum, by direct microscopical examination, and by cultural tests.The flasks are then inoculated and incubated for 48 hours at 37? C., and are placed in a horizontal position in the inciibator.A dense growth of typhoid bacilli is obtained with the flasks in this position, owing to the fact that the typhoid bacillus grows more readily in the presence of an abundant supply of oxygen. All the apparatus, with the exception of the bottles, is sterilised in the autoclave for three-quarters of an hour at 120? C. The bottles are sterilised by dry heat.The contents^ of a series of flasks are then mixed and measured in a graduated jar; a batch of culture as a rule consists of about 4 litres before it is diluted. Measured volumes of culture are then run off into suitable flasks by means of " two-way tubes."These tubes are then removed, and samples of the growth taken and tested for purity. This precaution is necessary in the preparation of all vaccines, but more especially so when a large quantity is prepared from many flasks. The flasks are closed with their original plugs, which are then covered with waxed paper. This is perforated in order that an even pressure may be maintained, thus ensuring that the temperature of the culture will correspond with the control flask in the bath. The flasks are then placed in a water-bath at a temperature of 45? C. A thermometer placed in the control flask will enable one to ascertain the exact temperature of the culture.The bath is kept at a temperature of 45? G. for half an hour to allow the temperature of the culture to rise to that of the bath. The temperature of the whole is then gradually raised until the thermometer inside the control flask stands at 53? C.After an hour and ten minutes at 53? C., during which time the flasks 'are repeatedly shaken, they are taken out of the bath and cooled down. The reason for this cooling is that it has been found by experiment that the potency of ...