In any series of infantile eczema cases studied by means of the cutaneous reactions to foreign proteins, the most perplexing problem which one encounters is the interpretation of reactions found positive to foods which, as such, have never entered the infant's diet. The frequent finding of a marked egg white reaction in early infancy, demonstrable on repeated applications, often in those exclusively breast fed, is the most notable example. Various explanations have been offered for such sensitizations. The most natural suggestion is that they are inherited, but, as Cooke and Vander Veer1 have shown, the factor of inheritance seems limited to a tendency to develop sensitizations, a specific sensitization in the descendant rarely being traceable to the antecedents. A temporary transfer by the mother, such as is shown by animals, would not explain the delayed appearance of sensitization so often observed in infants, even if one assumed that the