Page:Popular Science Monthly Volume 48.djvu/691

Rh Inheritance is unfortunately a word which is not always used with scientific precision. Most of the qualities which give a horse its value, as compared with other horses, are due to breeding, but this word has many meanings. Orlando says: "His horses are bred better; for besides that they are fair with their feeding, they are taught their manage, and to that end riders dearly hired." The "breeding jennet, lusty, young, and proud," seems to be a wild mare, with no breeding in the first sense, and the horse which did not lack what a horse should have, "round-hoofed, short-jointed, fetlocks shag and long. Broad breast, full eye, small head, and nostrils wide. High crest, short ears, straight legs, and passing strong. Thin mane, thick tail, broad buttocks, tender hide," is a thoroughbred.

Recent speculations have enforced attention to the difference between these meanings of the word. In the last sense breeding is the influence of ancestry, and it may practically be treated as synonymous with the word ancestry.

In the first sense breeding, broadly used, is that influence of the ontogenetic environment for which that most objectionable term "acquired characters" has been thoughtlessly adopted.

In his earlier writings Galton, borrowing, I suppose, from the Tempest, uses the word "nurture" to designate it, and this term is so apt and expressive that it should not pass out of use, for it may be given a definite technical meaning without violence to its ordinary use.

Using nurture instead of acquired characters for the influence of the environment of the individual, we may speak of the two elements of breeding as ancestry and nurture.

At the present day it is obvious that our studies of inheritance can have little value unless we distinguish between these two factors, for many naturalists hold that there is good ground for questioning whether the effects of nurture are ever inherited, and most naturalists admit the possibility that the value of these two factors may be very different.

If breeding is to be studied by the statistical method for the purpose of exhibiting the laws of inheritance, we must employ types in which we can separate the effects of ancestry from the effects of nurture; for if we make use of types which do not admit of this analysis, our results may tell us no more of inheritance than the scheme of prices tells us of the value of blood in horses.

If, as many teach, inheritance is equivalent to ancestry, and nurture is not inherited, no type in which these two factors are combined can tell us anything about inheritance.

It seems probable from Galton's data regarding the resemblance between the finger marks of fraternal couples that this is due to nurture in the broad sense of the word, and not to