We have seen that Mr.
Darwin himself implicitly admits the principle of specific stability in asserting the singular inflexibility of the organization of the goose.

We have also seen that it is not fair to conclude that all wild races can vary as much as the most variable domestic ones.

It has also been shown {127} that there are grounds for believing in a tendency to reversion generally, as it is distinctly present in certain instances.

Also that specific stability is confirmed by the physiological obstacles which oppose themselves to any considerable or continued intermixture of species, while no such barriers oppose themselves to the blending of varieties.

All these considerations taken together may fairly be considered as strengthening the belief that specific manifestations are relatively stable.