316 MK. c. c. hurst: experimental studies 



segregation aud gametic purity. Both agree, too, iu tbe con- 

 clusion that these factors appear to be carried by albinos in a 

 latent state. 



The " panachure " in mice, however, seems to differ from the 

 Dutch markings in rabbits, in so far that it appears to be com- 

 pletely recessive to self-colour or uniform coat ; while, on the 

 other band, the Dutch markings, so far as observed, are neither 

 recessive nor dominant to self-colour, giving variable hybrids, the 

 majority of which have white markings tending towards Dutch 

 markings. Occasionally, however, self-coloured hybrids appear, 

 but, so far, no true Dutch-marked. 



Another apparent difference between the " panachure " in mice 

 and the Dutch markings in rabbits is that the latter seem to be 

 more definite in character, with the pigment more localized than 

 in the variable spotted mice. Further experiments with Dutch 

 rabbits are now in progress in order to work out, if possible, 

 some of these interesting details. 



As will be seen from the list of references, the literature 

 relating to the heredity of coat-colour in mice has been very 

 extensive during the past two years, and space will not allow 

 any detailed references to the important experiments of 

 Cueuot, Darbishire, and Allen, and the valuable work of Bateson 

 and Castle in the Mendelian interpretation of present and past 

 records. Judging from my experience with rabbits, I am inclined 

 to think that most, if not all, of the various complications and 

 diflBculties met with in the various experiments with mice 

 may be interpreted by means of the simple Mendelian principles 

 (bearing in mind the important results gained by Cuenot, in 

 regard to the carrying of latent factors by albinos) without 

 recourse to such interesting though complicated conceptions as 

 mosaic gametes and resolution of compound characters. 



Summary. 



Experiments in crossing Belgian rabbits with albino Angoras, 

 aud the subsequent interbreeding of the hybrids, have demon- 

 strated the existence of 4 pairs of unit characters, viz. : — (1) Short 

 and Angora coat ; (2) Normality and albinism ; (3) Grey aud 

 black coat ; (4) Self-colour and Dutch markings. Each of these 

 pairs is inherited independently of the other, so that all kinds 

 of combinations occur among the offspring (see Table 29, p. .320). 



