VARIATION UNDER BOMEaTIGATION. \\ 



cases could be given among animals and plants. Prom 

 (acts collected by Heusinger, it appears that white sheep 

 and pigs are injured by certain plants, while dark-colored 

 individuals escape: Professor Wyraan 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" (t. 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; pigeons 

 with feathered feet have skin between their outer toes; 

 pigeons witl^ 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 cer- 

 tainly modify unintentionally other parts of the structure, 

 oyving to the mysterious laws of correlation. 



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 structure and con- 

 stitution in which the varieties and sub-varieties differ 

 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 consider- 

 able physiological importance, are endless. Dr. Prosper 

 Lucas' treatise, in two large volumes, is the fullest 

 and the best on this subject. No breeder doubts how 

 strong is the tendency to inheritance; that like pro- 

 duces like is his fundamental belief : doubts have 

 been thrown on this principle only by theoretical 

 writers. When any deviation of structure often appears, 

 and we see it in the father and child, we cannot tell 

 whether it may not be due to the same cause having acted 



