Published online by Cambridge University Press: 15 May 2009
In previous reports (Watson 1937 a, b) one of us has described a series of experiments in which various diets were tested in regard to their effect on the growth, fertility, survival and resistance of mice. It was found that, when part of the oatmeal in a particular diet was replaced by dried skimmed milk, the does were more fertile, and the young mice gained weight more rapidly and showed a lower mortality during the first 8 weeks of life. Mice bred and reared on the latter diet were found to show a significantly increased resistance to per os infection with living cultures of Bact. typhi-murium, and to the intraperitoneal injection of a toxic fraction derived from that organism. The results obtained in a few tests suggested that these mice were also more resistant to the intraperitoneal injection of living Bact. typhi-murium; but the differences observed were smaller, and of doubtful significance. In the present paper we record the effect of these two diets on the epidemic spread of mouse-typhoid.