In Science for November 24, 1911, Osborne and Mendel reviewed briefly their experience in feeding isolated food substances to albino rats.2 The results of these experiments are so important and far reaching that it seemed desirable to repeat some of the work on another species. Albino mice were chosen because they are omnivorous, nearly as easy to handle as rats, apparently less susceptible to lung diseases, cost less to feed, being only about one-tenth as heavy as rats of corresponding age, and have an even shorter life span. Miss A. E. C. Lathrop of Granby, Massachusetts, who has had a long experience in breeding mice, says that the average life of a white mouse is a little less than two years. They are sexually mature at two months and fully grown at 150 days or less.
With the exception of experiments of Rohmann,S details of which have not yet been published, mice have not been kept alive much longer than a month on food containing a single protein; Lunin4 fed casein as the only protein, as did Hall5 also; the latter 1 This investigation was made possible through the assistance of Drs. Thomas B. Osborne and Lafayette B. Mendel in connection with the Carnegie Institution of Washington. The helpful co-operation of Miss Edna L. Ferry merits special acknowledgement here.