In this paper, a new gene is described in the house mouse which arose, presumably by a spontaneous mutation, in one of our stocks. The genetics of the case are rather simple and can be dealt with shortly. The main attempt is to show how manifold may be the effect of one single Mendelian factor, and to demonstrate that the primary effects caused by a factor lead to a chain of secondary and tertiary alterations which, although ultimately caused by that hereditary unit, are only associated with it more or less mechanically. Since we usually see only the more remote consequences of the action of a gene, the goal of such an investigation should be to trace all secondary and tertiary actions back to that stage in development to which all the manifold effects converge, the original starting-point of an anomaly. In other words, we have an experiment in embryology in a reversed direction; while in experimental embryology the experiment is known, but the result is doubtful, here we have to study the results first and by going backwards to find out what sort of an experiment nature has performed. Since this process is long and laborious, only the very first steps can be demonstrated here. This paper is confined to the investigation of bones and teeth. In a later communication the author hopes to be able to deal with the inner organs, embryology, and some physiological problems which arise from this work.
A new sub-lethal colour mutation in the house mouse