The mutation theory; experiments and observations on the origin of species in the vegetable kingdom . ble conditions. These trifoliate leaves obviously Atavism by Seeds and Buds. 109 constitute a reversion to the normal clover leaf but, onthe other hand, they are merely the extreme variants inthe curve of the five-leavedrace (Fig. 6, p. 48). Asimilar state of affairs pre-vails in numerous cases ofsemilatency where the rangeof variation of a characteris occasioned by the antag-onism of two characters. Mutational atavism mustobviously be as rare as mu-tation itself. The reversionof striped flowe
The mutation theory; experiments and observations on the origin of species in the vegetable kingdom . ble conditions. These trifoliate leaves obviously Atavism by Seeds and Buds. 109 constitute a reversion to the normal clover leaf but, onthe other hand, they are merely the extreme variants inthe curve of the five-leavedrace (Fig. 6, p. 48). Asimilar state of affairs pre-vails in numerous cases ofsemilatency where the rangeof variation of a characteris occasioned by the antag-onism of two characters. Mutational atavism mustobviously be as rare as mu-tation itself. The reversionof striped flowers to self-colored ones, the heritableatavism of Plantago laneeo-lata ramosa, and the incon-stancy of the peloric Lina-ria, are facts which we shallhave to consider below. Physiological atavismcan be manifested by plantspropagated by seeds or bybuds. In the case of theformer definite proof isonly possible under excep-tionally favorable circum-stances ; in the case of thelatter it is at once evident(Fig. 16 at A). The pub-lished records of atavismin crops of seedlings arealways subject to the sus-. Fig. i6. Ccphalotaxus pcdunculatafastigiato. The main stem bearsthe upright branches with leavesinserted on all sides, character-istic of the variety; but has pro-duced at A, where a branch hasbeen cut off close, severalbranches with flat spreading bi-serial leaves such as are char-acteristic of the parent species. 110 A/aiisiii. ])icions indicated above. T mean that they occur so rarelyand in so few indixidnals tliat the possibihty of a previouscross, by means of insects, with the pohen of alhed forms,even if growing a long way off, can never be quite ex-cluded. It is only in cases in which, as in that of Ocno-ihcra sciutilhvis ( \^ol. I, pp. 245 and 2)77), a species pro-duces a large number of atavistic individuals every year,that the phenomenon easily lends itself to experimentalstudy. On account of the circumstances indicated, it is notpossible to say whether atavism in plants pro
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