Atavism by Seeds and Buds. 



109 



constitute a reversion to the normal clover leaf but, on 

 the other hand, they are merely the extreme variants in 

 the curve of the five-leaved 

 race (Fig. 6, p. 48). A 

 similar state of affairs pre- 

 vails in numerous cases of 

 semilatency where the range 

 of variation of a character 

 is occasioned by the antag- 

 onism of two characters. 



Mutational atavism must 

 obviously be as rare as mu- 

 tation itself. The reversion 

 of striped flowers to self- 

 colored ones, the heritable 

 atavism of Plantago laneeo- 

 lata ramosa, and the incon- 

 stancy of the peloric Lina- 

 ria, are facts which we shall 

 have to consider below. 



Physiological atavism 

 can be manifested by plants 

 propagated by seeds or by 

 buds. In the case of the 

 former definite proof is 

 only possible under excep- 

 tionally favorable circum- 

 stances ; in the case of the 

 latter it is at once evident 

 (Fig. 16 at A). The pub- 

 lished records of atavism 

 in crops of seedlings are 

 always subject to the sus- 



Fig. i6. Ccphalotaxus pcdunculata 

 fastigiato. The main stem bears 

 the upright branches with leaves 

 inserted on all sides, character- 

 istic of the variety; but has pro- 

 duced at A, where a branch has 

 been cut off close, several 

 branches with flat spreading bi- 

 serial leaves such as are char- 

 acteristic of the parent species. 



