VARIATION UNDER DOMESTICATION 37 



ear, from the animals being seldom much, alarmed, seems 

 probable. 



Many laws regulate variation, some few of which can 

 be dimly seen, and will hereafter be briefly discussed. I 

 will here only allude to what may be called correlated 

 variation. Iniportant changes in the embryo or larva 

 will probably entail changes in the mature animal. In i 

 monstrosities, the correlations between quite distinct parts 

 are very curious; and many instances are given in Isidore 

 Geoffroy St.-Hilaire's great work on this subject. Breeders 

 believe that long limbs are almost always accompanied 

 by an elongated head. Some instances of correlation 

 are quite whimsical: thus cats which are entirely white \ 

 and have blue eyes are generally deaf; but it has been 

 lately stated by Mr. Tait that this is confined to the 

 males. Color and constitutional peculiarities go together, 

 of which many remarkable cases could be given among 

 animals and plants. From facts collected by Heusinger, 

 it appears that white sheep and pigs are injured by cer- 

 tain plants, while dark-colored individuals escape: Pro- 

 fessor Wyman has recently communicated to me a good 

 illustration of this fact; on asking some farmers in Vir- 

 ginia how it was that all their pigs were black, they 

 informed him that the pigs ate the paint-root (Lachnan- 

 thes), which colored their bones pink, and which caused 

 the hoofs of all but the black varieties to drop o£f; and 

 one of the "crackers" (i.e., Virginia squatters) added, 

 "we select the black members of a litter for raising, as 

 they alone have a good chance of living." Hairless dogs 

 have imperfect teeth; long-haired and coarse-haired ani- 

 mals are apt to have, as is asserted, long or many horns; 

 pigeons with feathered feet have skin between their outer 



