March 10, 1922] 



SCIENCE 



269 



tions with many bars, and the rays are large 

 and composite or heterogeneous. The natural 

 conclusion is that this wood must be from 

 some species of Ilex. 



This finding has since been confirmed by the 

 Forestry Officer of British Guiana. 



Samuel J. Record 

 Yale University 



SPECIAL ARTICLES 

 GENETICS OF THE VIENNA WHITE RABBIT 



In the second edition of his text-boolc', Dr. 

 Erwin Baur described a cross between two 

 white varieties of rabbit which produced 

 colored young. One of the white varieties is 

 the familiar pink-eyed albino', the other is 

 called Vienna White and is described by Bam- 

 as differing from the albino variety only in 

 the color of the eyes, which are blue. He ex- 

 plains the production of colored young in this 

 cross as due to the Complementary action of 

 two independent color factors, like the well 

 known cases among plants in which a cross 

 between two white-flowered varieties produces 

 jprogeny bearing colored flowers. 



It happens that the colored young rabbit 

 figured by Baur as resulting from the cross 

 was Dutch marked, and this led Punnett to 

 suppose that the blue-eyed white parent was 

 really a Dutch rabliit in which the white areas 

 had attained a maximum extension so as to 

 cover the entire coat. This interpretation 

 seemed reasonable to me until I recenth' ob- 

 tained in some breeding experiments animals 

 similar to Baur's Vienna Whites, when it be- 

 came clear that they have no relation to Dutch 

 marking, and also that the relation of Vienna 

 White to albinism is much closer than Baur 

 had supposed. 



The color factor of Vienna White is in fact 

 an allelomorph of albinism. If Baur had used 

 in the cross with Vienna White an albino 

 whose parents were yellow, he would not have 

 obtained colored young but only blue-eyed 

 whites or albinos, which result would have 

 shown that the two white varieties are not due 



1 Einf iihrung in die experimentelle Vererbungs- 

 lehre, Berlin, 1914. 



to complementary factors but to allelomorphic 

 conditions of one and the same factor. 



The case is strictly analogous with that of 

 the silver agouti guinea-pig as worked out by 

 Castle and Wright^ several years ago. The 

 so-called color factor has in guinea-pigs several 

 allelomorphic states, as shown by Wright. 

 The two with which we were then concerned 

 produce respectively (1) the ordinary albino or 

 all-white coat associated with pink-eyes and 

 (2) a condition in which the coat develops 

 black pigment but no yellow pigment, and the 

 eyes are red, not pink. By suitable crosses the 

 gene for yellow coat can be introduced into the 

 red-eyed variety. But since (1) the gene for 

 yellow inhibits the development of black pig- 

 ment in the coat and (2) the gene for red-eye 

 (the color allelomorph) inhibits the develop- 

 ment of yelloiv in the coat, it follows that the 

 coat, in what is genetically a red-eyed yellow 

 animal, contains neither black nor yellow pig- 

 ment and so is white. Only the red eye-color 

 then serves to distinguish the animal from an 

 albino. It is in fact a red-eyed white in ap- 

 pearance, but genetically is a red-eyed yellow 

 ,and if crossed with yellow animals will pro- 

 duce yellow young. 



Now in rabbits we have a strictly parallel 

 situation. The chinchilla^ rabbit correspond'j 

 with the red-eyed silver agouti guinea-pig. Its 

 coat contains black pigment but not yellow. 

 If we cross chinchilla with albino, we obtain 

 chinchilla young, not gray, indicating that chin- 

 chilla and albinism are allelomorphs, not com- 

 plementary factors. If the albino parent car- 

 ries the gene for yellow coat, then in F^ we 

 obtain chinchillas, albinos, and "blue-eyed 

 whites." The last are obviously yellow chin- 

 chillas. I have not been able to obtain as yet 

 the Vienna White variety from Europe, but 

 those who have them can easily put this inter- 

 pretation to the test by crossing Vienna White 

 with a yellow coated variety. If my interpreta- 

 tion is con-eet, they will obtain yellow young 

 from the cross. 



2 Carnegie Institution of Wash., Publ. No. 241, 

 1916. 



3 Castle, W. E., Genetics of the ehinchilla 

 rabbit. Science, April 22, 1921. 



