Summary.-The evolution and structure of adenomatous polyps and adenocarcinomata of the colon in NMRI mice induced by dimethylhydrazine are described. Severe toxic reactions in the liver and other organs are produced by dimethylhydrazine (DMH), but tumours are induced only in the colon and around the anus.The 100%o incidence and growth characteristics of the tumours make it potentially a good model system, but investigators should take into account the widespread nonspecific cellular injury induced by this carcinogen.

The effect of a number of explanatory variables on the degree of physiological jaundice in mature infants was evaluated by multiple regression analysis. The sampling was designed so that comparisons could be made between siblings. We found an effect of gestational age, gender, infant nutrition, ABO incompatibility and induction of labour. Taking these factors into account we still found a highly significant correlation between the peak bilirubin levels of siblings. Whether this correlation is genetically or environmentally determined is not clear.

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