VARIATION UNDER DOMESTICATION 9 



seen, and will hereafter be briefly discussed. I will here only allude 

 to what may be called correlated variation. Important changes in 

 the embryo or larva will probably entail changes in the mature 

 animal. In monstrosities, the correlations between quite distinct 

 parts are very curious; and many instances are given in Isidore 

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

 lieve that long limbs are almost always accompanied by an elon- 

 gated head. Some instances of correlation are quite whimsical; 

 thus cats which are entirely white and have blue eyes are gener- 

 ally 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 certain plants, while dark- 

 colored individuals escape: Professor Wyman has recently com- 

 municated to me a good illustration of this fact; on asking some 

 farmers in Virginia how it was that all their pigs were black, they 

 informed him that the pigs ate the paint-root (Lachnanthes), 

 which colored their bones pink, and which caused the hoofs of all 

 but the black varieties to drop off: and one of the "Crackers" 

 (#, 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 

 animals are apt to have, as is asserted, long or many horns; pi- 

 geons with feathered feet have skin between their outer toes; pi- 

 geons with short beaks have small feet, and those with long beaks 

 large feet. Hence if man goes on selecting, and thus augmenting, 

 any peculiarity, he will almost certainly modify unintentionally 

 other parts of the structure, owing to the mysterious laws of cor- 

 relation. 



The results of the various, unknown, or but dimly understood 

 laws of variation are infinitely complex and diversified. It is well 

 worth while carefully to study the several treatises on some of our 

 old cultivated plants, as on the hyacinth, potato, even the dahlia, 

 etc.; and it is really surprising to note the endless points of struc- 

 ture and constitution in which the varieties and sub-varieties dif- 

 fer slightly from each other. The whole organization seems to have 

 become plastic, and departs in a slight degree from that of the 

 parental type. 



Any variation which is not inherited is unimportant for us. But 

 the number and diversity of inheritable deviations of structure, 

 both those of slight and those of considerable physiological im- 

 portance, are endless. Dr. Prosper Lucas' treatise, in two large 



