16 BIONOMIC LAWS. 
should be observed that it is not every kind of selection that produces 
transformation. It is only as selection results in the preservation of 
other than average forms that it has any influence in transforming a 
race. The selection of average forms for propagation tends to pro- 
duce stability of type; and the selection of extreme, but of opposite, 
and, therefore, balanced deviation from the type produces fluctuating 
variation; but unbalanced selection, that is, propagation from forms 
whose average character differs from the average character of the 
race, changes in some degree the average character of the race in the 
next generation. Whenever this takes place, whether it be by the 
design of man or not, there transformation takes place. 
Unbalanced artificial selection is not the only principle producing 
the unbalanced propagation of the variations of domestic races. Un- 
balanced natural selection caused by change in climate or in other 
external conditions, and resulting in the superior success of other 
than average forms, will also produce unbalanced propagation of 
domestic as well as of wild races. Again, it may be that some form 
of variation that is above the average in strength or skill, or in the 
length of natural weapons, or in the beauty of its adornments, will 
gain an advantage over its fellows in the appropriation of food or 
in winning mates, and so become subject to some form of reflexive 
selection, by which unbalanced propagation is produced. 
There may also arise unbalanced elimination, when, through some 
overwhelming catastrophe, a large portion of the domestic stock is 
destroyed, and the remaining individuals that propagate do not repre- 
sent the average characteristics of the race. This may be called 
indiscriminate elimination. Indiscriminate elimination arises when 
war, famine, pestilence, or earthquake falling upon a tribe of men 
results in the indiscriminate destruction of nearly all of their domestic 
animals; and in many of these cases the surviving individuals from 
which the stock is afterward propagated do not represent the average 
character of the previous stock. 
Again, some variation of the stock may be endowed with a degree 
of fecundity decidedly above the average fecundity of the rest of the 
stock; and, if the form possessing this superior fecundity is as well 
adapted as other forms to meet the desires of those who raise the 
creatures, unbalanced propagation will take place, and the average 
character of the stock will be changed. In my paper on Intensive 
Segregation* I call this principle fecundal transformation. Karl 
Pearson has discussed this principle under the title of ‘‘reproductive 

* See Appendix II. 
