Part I - Page 2

become hereditary], when not so become simple variety, when it does a race. Each[41] parent transmits its peculiarities, therefore if varieties allowed freely to cross, except by the chance of two characterized by same peculiarity happening to marry, such varieties will be constantly demolished[42]. All bisexual animals must cross, hermaphrodite plants do cross, it seems very possible that hermaphrodite animals do cross,--conclusion strengthened: ill effects of breeding in and in, good effects of crossing possibly analogous to good effects of change in condition [[?]] [43].

[41] The position of the following passage is uncertain. "If individuals of two widely different varieties be allowed to cross, a third race will be formed--a most fertile source of the variation in domesticated animals. [[In the Origin, Ed. i. p. 20 the author says that "the possibility of making distinct races by crossing has been greatly exaggerated."]] If freely allowed, the characters of pure parents will be lost, number of races thus [[illegible]] but differences [[?]] besides the [[illegible]]. But if varieties differing in very slight respects be allowed to cross, such small variation will be destroyed, at least to our senses,--a variation [clearly] just to be distinguished by long legs will have offspring not to be so distinguished. Free crossing great agent in producing uniformity in any breed. Introduce tendency to revert to parent form."

[42] The swamping effect of intercrossing is referred to in the Origin, Ed. i. p. 103, vi. p. 126.

[43] A discussion on the intercrossing of hermaphrodites in relation to Knight's views occurs in the Origin, Ed. i. p. 96, vi. p. 119. The parallelism between crossing and changed conditions is briefly given in the Origin, Ed. i. p. 267, vi. p. 391, and was finally investigated in The Effects of Cross and Self-Fertilisation in the Vegetable Kingdom, 1876.

Therefore if in any country or district all animals of one species be allowed freely to cross, any small tendency in them to vary will be constantly counteracted. Secondly reversion to parent form--analogue of vis medicatrix[44]. But if man selects, then new races rapidly formed,--of late years systematically followed,--in most ancient times often practically followed[45]. By such selection make race-horse, dray-horse--one cow good for tallow, another for eating &c.--one plant's good lay [[illegible]] in leaves another in fruit &c. &c.: the same plant to supply his wants at different times of year. By former means animals become adapted, as a direct effect to a cause, to external conditions, as size of body to amount of food. By this latter means they may also be so adapted, but further they may be adapted to ends and pursuits, which by no possibility can affect growth, as existence of tallow-chandler cannot tend to make fat. In such selected races, if not removed to new conditions, and [[if]] preserved from