CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE 

 MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD COLLEGE. 

 E. L. MARK, DIRECTOR. — No. 142. 



THE HEREDITY OF ALBINISM. 



By W. E. Castle and Glover M. Allen. 



Received March 11, 1903. 

 COKTENTS. 



PAGE 



I. Introduction 603 



II. Complete Albinism a Recessive Character 604 



(a) In Mice 604 



(6) In Otiier Mammals, in Fislies, and in Plants 606 



III. Partial Albinism a Mosaic of Dominant and Recessive Characters, and 



a Unit in Heredity 606 



IV. Pure and Hybrid Mosaics 611 



V. Pure and Impure Recessives 613 



VI. Cross-breeding, Reversion, and the Doctrine of Gametic Purity . . . 617 



VIL Summary 619 



Bibliography 620 



I. Introduction. 



This paper contains a preliminary statement of certain results of 

 breeding experiments with mice, guinea-pigs, and rabbits, which have 

 been conducted in the Zoological Laboratory of Harvard University 

 during the last two and a half years. The experiments with mice are 

 the work principally of the junior author ; those with guinea-jDigs and 

 rabbits, of the senior author. 



Albinism, or absence of the normal pigmentation of an organism, is a 

 not infre(iuent phenomenon in both animals and plants, yet its occurrence 

 in nature is sporadic and has usually been interpreted as an indication of 

 organic weakness. But this interpretation is probably erroneous, for 

 albino races of domesticated animals are apparently not inferior in vigor 

 to other races. Such is demonstrably the case with albino mice. 



The idea that albinos lack constitutional vigor may have its origin in 

 the observation that, in crosses between albinos and normal individuals, 



