to form Varieties. 



6305 



not return to the original form ; for that form is an inferior one, and 

 could never compete with it for existence. Granted, therefore a " ten- 

 dency" to reproduce the original type of the species, still the variety 

 must ever remain preponderant in numbers, and under adverse physical 

 conditions again alone survive. But this new, improved, and populous 

 race might itself, in course of time, give rise to new varieties, ex- 

 hibiting several diverging modifications of form, any of which, tending 

 to increase the facilities for preserving existence, must, by the same 

 general law, in their turn become predominant. Here, then, we have 

 progression and continued divergence deduced from the general laws 

 which regulate the existence of animals in a state of nature, and from 

 the undisputed fact that varieties do frequently occur. It is not, how- 

 ever, contended that this result would be invariable ; a change of 

 physical conditions in the district might at times materially modify it, 

 rendering the race which had been the most capable of supporting 

 existence under the former conditions now the least so, and even 

 causing the extinction of the newer, and for a time superior, race, 

 while the old or parent species and its first inferior varieties con- 

 tinued to flourish. Variations in unimportant parts might also occur, 

 having no perceptible effect on the life-preserving powers ; and the 

 varieties so furnished might run a course parallel with the parent 

 species, either giving rise to further variations or returning to the 

 former type. All we argue for is, that certain varieties have a tendency 

 to maintain their existence longer than the original species, and this 

 tendency must make itself felt; for though the doctrine of chances or 

 averages can never be trusted to on a limited scale, yet, if applied to 

 high numbers, the results come nearer to what theory demands, and, 

 as we approach to an infinity of examples, become strictly accurate. 

 Now the scale on which nature works is so vast — the numbers of indi- 

 viduals and periods of time with which she deals approach so near to 

 infinity, that any cause, however shght, and however liable to be veiled 

 and counteracted by accidental circumstances, must in the end pro- 

 duce its full legitimate results. 



Let us now turn to domesticated animals, and inquire how varieties 

 produced among them are affected by the principles here enunciated. 

 The essential difference in the condition of wild and domestic animals 

 is this, — that among the former, their well-being and very existence 

 depend upon the full exercise and healthy condition of all their senses 

 and physical powers, whereas, among the latter, these are only par- 

 tially exercised, and in some cases are absolutely unused. A wild 

 animal has to search, and often to labour, for every mouthful of food 

 XYI, 3 M 



