ANATOMICAL COMPARISON BETWEEN THE ADRENAL GLANDS OF WILD NORWAY, WILD ALEXANDRINE AND DOMESTIC NORWAY RATS1

Abstract

Our knowledge of the effects produced by domestication on the endocrine system of animals is very limited, owing in large part to the fact that domesticated and wild forms of the same animal are rarely available simultaneously. The common Norway rat, however, constitutes a definite exception to this statement, since it has many representatives of both domestic and wild forms alive at the present time. Domestic Norways have been reared in laboratories throughout the world for the past 60 years or more, while the wild Norways still live in alleys, yards, cellars and houses and also have a world wide distribution. The domestic rats are tame, tractable, do not attempt to escape, and reproduce well in captivity; the wild rats usually live in burrows in the ground and are fierce, savage, suspicious, and make every effort to resist captivity. Except under particularly favorable conditions, they have not been successfully reared in captivity.