INHERITANCE OF WHITE-SPOTTING IN RABBITS. 5 



interest attaches to the inheritance of these patterns in crosses, a 

 subject which has been studied for some years at the Bussey Institu- 

 tion. The present paper will deal with the subject of white-spotting 

 in domestic rabbits. 



Patterns of white-spotting mendelize without known exception 

 but with some irregularity as regards dominance. In some cases 

 white-spotting is not expressed in the heterozygote, but if expressed 

 at all in the heterozygote its expression is always stronger yet in tlie 

 homozygote. When the character is nearly or quite suppressed in 

 the heterozj'gote, we may call it recessive; when the character is 

 strongly expressed in the heterozygote, we may call it dominant. But 

 neither term is applicable without qualification in the way that 

 recessive is applicable to complete albinism in rodents. 



With this qualification of terms, it may be said that there occur 

 among domestic rabbits two forms of white-spotting, probably of 

 independent origin and certainly of quite different genetic behavior, 

 since one is recessive and the other dominant in crosses with the 

 same race of unspotted rabbits. The dominant form of white-spotting 

 is found in the so-called English rabbit and its inheritance has been 

 discussed by Castle and Hadley (1915). The recessive form of white- 

 spotting is found in Dutch rabbits, as observed independently by 

 Hurst and by Castle. Punnett assents to this conclusion with the 

 qualification that the inheritance is possibly not that of a simple 



(one-factor) sort. ^, ,^^, , 



^ ' DUTCH. 



In September 1910 three standard-bred Dutch rabbits were obtained 

 from a fancier who had bred and exhibited prize-winning animals 

 derived from stock imported from England. They resembled grades 

 7, 8, and 9 respectively (plate 1). The female proved to be sterile 

 and was ultimately discarded. One of the males (cf3037, grade 7) 

 was mated with two heterozygous English does, which produced 

 self-colored blacks as recessives when mated with English bucks of 

 their own race. For the present we shall consider only the non- 

 English young produced by these matings. Such young would be of 

 the same character as those produced by self-colored ani- 

 mals mated with Dutch, since they would arise from a se// 

 gamete furnished by the mother and this would be fer- 

 tilized by a Dutch gamete furnished by the father. Six 

 young of this character were produced of the accom- 

 panying grades. 



This same male was mated also with 3 Himalayan albino 

 does of a race entirely free from spotting but which 

 lacked the color factor. Potentially these does were self- 

 colored. This cross produced 18 young of the accom- 

 panying grades. (See table 13) 



' Grade signifies a self animal, i.e., one without white spotting. 



