70 THE MENDEL JOURNAL 



instance of reversion to an ancestral type resulting 

 from crossing the two species. ■•• However that may- 

 be, the point to be noticed is that the foal differed 

 from both parents. Hence the possibility of the 

 origin of the Blotched Tabby from crossing the 

 European and African Wild Cats. When tested 

 by experiment, however, this suggestion broke down. 

 In the Zoological Gardens I crossed a pure-bred male 

 Scotch Wild Cat with a female African Wild Cat from 

 Uganda, which had never previously kittened. The 

 result was, as I expected, a litter of three kittens 

 exactly resembling the Striped Tabby. Only one of 

 these kittens lived to be half grown. By that time 

 she had almost lost the very distinct pattern of 

 kittenhood, and was becoming daily more like her 

 mother, in which the pattern was evanescent. | 



* Mendelian experiments throw a new light on this phenomenon 

 of reversion. A "reversionary character'' is a compound one, and 

 is only made manifest when two or more factors react upon each 

 other-. If the factors are separated, and one is carried in one 

 individual and the other in another, then the "reversionary charac- 

 ter" may remain unrevealed for generations, and will only become 

 patent as soon as two parents which carry between them the com- 

 plementary factors are mated together. Black mice, rats, and 

 rabbits may be mated to certain albinoes without begetting any 

 gi'ey (brown) individuals among their offspring. Yet, when mated 

 with other albinoes, young ones having the grey or reversionary 

 colour of the wild type will appear. This is due to the fact that 

 colour is a compound character, and that grey is due to the meeting 

 of two complementary factors, one of which is carried by the black 

 parent and the other, in the cases we are considering, by certain 

 albinoes, which carry the factor determining greyness. Other albinoes 

 lack this factor, but carry that which determines some other colour, 

 such as blackness for instance. The reversionary colour greyness 

 can therefore only be produced when an albino carrying the grey 

 determiner is mated to some other coloured partner, such for instance 

 as a black one. But if such a partner be mated with albinoes 

 carrying the black complementary factor, the only colour that will 

 appear among the oft'spring will be black. — Editor. 



t P. Z. S., 1908, pp. 749-750, text figs. 194-195. 



