Heredity of Hair-Length in Guinea-Pigs and Its Bearing on the Theory of Pure Gametes By W. E. Castle and Alexander Forbes: The Origin of a Polydactylous Race of Guinea-Pigs

By W. E. Castle and Alexander Forbes. 1. INTRODUCTION. In earlier papers (C astle, :o3, :o5) it has been shown by one of us that long or Angora coat in guinea-pigs and rabbits is alternative in heredity to normal or short coat. It has been shown further that in cross-breeding normal or short coat dominates over long coat, in conformity with Mendel slaw of heredity, but that the purity of the gametes formed by cross-breds is not absolute. Impurity of the gametes is indicated by two facts: First, the number of long-haired young produced by cross-bred parents is in excess of the Mendelian proportion, one-fourth; secondly, many of these long-haired young show an imperfect development of the long-haired character, as compared with their long-haired ancestors. Both these facts may be explained by supposing that the alternative characters, short and long hair, which are present in the cross-breds one seen, the other unseen have in many cases failed to segregate, or have segregated only imperfectly, when gametes have been produced by the cross-breds. Accordingly the conformity with Mendel slaw is a qualified one. More extended and detailed studies made by us during the past year confirm these conclusions and add several new facts concerning the behavior in heredity of these alternative characters. The idea advanced tentatively by Castle (:05), that the hair-lengths of guinea-pigs form a discontinuous series of two, three, four or more times the length of short or normal hair, is found to be incorrect. Careful examination of the hair of several hundred guinea-pigs (mostly cross-breds) shows that there occur hairs of practically all lengths from 3.3 cm. up to about 23 cm. The series of supposed maximal hair-lengths of twice 4cm., thrice 4cm., etc., resulted from an insufficient number of observations.(Typographical errors above are due to OCR software and don't occur in the book.)About the Publisher Forgotte