Abstract
The present experiment dealing- with the addition of small traces of oil of gaultheria (true wintergreen oil) to the otherwise normal diet of mice, has given some interesting data. The mice used were individuals belonging to a highly inbred stock (the D strain). This stock is a branch of the dilute brown strain which has an unbroken line, mainly of brother-to-sister descent, extending over 25 years (Little and Murray). The inbreeding was initiated by Little and the stock is usually referred to as the Little Dilute Browns. My branch had passed through several individual laboratories before coming into my own. At present my dilute brown stock is in the tenth generation of pedigreed brother-to-sister matings.
Breeding females of this stock are very prone to develop spontaneous adeno-carcinoma of the breast. Murray, who has made more observations on the incidence of neoplasia in individuals of this stock than anyone else, has found more than 1300 spontaneous tumors in the past 5 years. Of all the female mice which are used as breeders, fully 80% develop carcinoma. The common infections are the cause of death of the remaining 20%. It is Murray's opinion that if all breeding females of this stock would live long enough they would all develop carcinoma of the breast.
My sub-line shows parallel findings, differing only in minor details. Whereas Murray reports 1300 spontaneous tumors, I have had only 115. This is due to the fact that individuals of other stocks in my laboratory have been better breeders and consequently have filled up most of my available cages. The incidence of spontaneous tumors in the individuals, however, is as high as it has been in the Murray derivatives of the dilute browns.
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