[164]

families of races has been replaced by others— The races of Auchenia, would naturally have gone on increasing in number, less favourable varieties being lost, & certain useful— types being multiplied, wider sub genera being formed, until a more powerful division being introduced— the numbers become stationary, decrease.— a few being retained, which naturally would be isolated, as in aberrant families & these at last would be lost.— As there is much relationship between Auchenias & Ruminants (& even Horses) so the chances are some one or two types of Auchenias might remain, for as long as mammiferous type is preponderant the number of divisions in it will be increasing).— As long as numbers of individuals in any great class remain constant or increase, the number of divisions will tend to increase, but as soon as they diminish, some of the forms will die out, for all the forms will change which decreases the total number will almost certainly affect some forms more than others.—

[164v]

If physical mutations of world go in cycle (probably endless combinations) yet organic not so, for each form bears impress of ancestors & is related not only to the cyclical external conditions, but to the progressive organic world.

11

We see sub-genera of dogs.— cabbages, potatoes.— Hence without seeking cause we might expect it in nature.— Cause no doubt is that when a form is domesticated it is distributed & exposed to many conditions & selected to vari various sub-ends.—

When a particularly variety happens to be formed it spreads largely & is again subjected to variation.

Should some analogous animal take place of dog, then is so much common in nature of all races of dogs that all probably would be exterminated.— Thus, we may instance Isid. G. St Hilaires prophecy that the tame Auchenias (are there many races?) of S. America will be lost through introduction of Cattle & Sheep & Horses in S. America.— So if Australia had breeds of Marsupials this would have happened.— Probably in plants some