'4 



BIl »N( »MIC LAWS. 



ordination between sex and sex, and between the sexual elements of 

 the group, .is will secure impregnation, and the production of both 

 male and female elements must be sufficient to prevent extinction. 



2. The Transformation oj Races. 



The survival of a race or species depends on its having sufficient 

 adaptation to the environment to secure maintenance, on there being 

 sufficient compatibility between the sexes to secure fertility, and on 

 the production of male and female elements in sufficient abundance 

 to secure fecundity; but the presence of these conditions does not 

 insure the transformation of the race or species enjoying these condi- 

 tions, nor does the extinction of races or species lacking in these con- 

 ditions insure transformation in the surviving forms. As domestica- 

 tion prevents or greatly impairs reproduction in the elephant, this 

 species does not survive under domestication and therefore escapes 

 the transformation necessary to produce a domestic race. For a 

 similar reason, the complete extermination of the American bison 

 would not produce a new race of bisons; and it could have influence 

 in transforming an associated species of some other family only in 

 case the absence of the bison should introduce a change in the relative 

 degrees of maintenance, compatibility, or fecundity possessed by the 

 different variations of the species, so that the most successful should 

 be other than those that were most successful during the period of 

 association with the bison. A little reflection will reveal the fact 

 that when the change of relative degrees of maintenance or fecundity 

 pertains to races or species which are entirely prevented from crossing 

 the relative numbers in which these groups exist will be changed, but 

 that this will not be a cause of change in the characteristics of the 

 groups, even if some of them become extinct. This will be distinctly 

 seen if we take a definite case. For example, during one year turkeys 

 may attract the attention of a poulterer, and the next year peafowls 

 may become his favorites ; but the change in the relative importance 

 given to either species transforms neither the one or the other. 

 Again, he may have a pair of a species which he would gladly multi- 

 ply, but through difficulty in getting them to mate his success may be 

 very limited; or in the case of a second desirable species that pairs 

 freely, diminished fecundity may interfere with their multiplication, 

 while at the same time a third species of no great value, but not 

 limited by these disabilities, multiplies freely and is raised in large 

 numbers. The point to be observed is that in all these cases the 

 difference in the degrees of propagation of these different species is 

 not a cause of transformation in the characteristics of the species. 



