Stability and Real Atavism 179 



of the same variety have been derived in this 

 way from one primitive, aberrant individual. 

 We may disregard variegated leaves, spotted or 

 marked with white or yellow, because they are 

 too inconstant types. 



We may next turn our attention to the va- 

 rieties of trees with cut leaves, as the oak- 

 leaved Laburnum, the parsley-leaved vine and 

 the fern-leaved birch. Here the margin of the 

 leaves is deeply cut and divided by many 

 incisions, which sometimes change only the 

 outer parts of the blade, but in other cases may 

 go farther and reach, or nearly reach, the mid- 

 vein, and change the simple leaf into a seem- 

 ingly compound structure. The anomaly may 

 even lead to the almost complete loss of all the 

 chorophyll-tissue and the greater part of the 

 lateral veins, as in the case of the cut-leaved 

 beech or Fagus sylvatica pectinata. 



Such varieties are often apt to revert by buds 

 to the common forms. The cut-leaved beech 

 sometimes reverts partially only, and the 

 branches often display the different forms of 

 cut-leaved, fern-like, oak-leaved and other vari- 

 ously shaped leaves on the same twigs. But 

 this is merely due to the wide variability of the 

 degree of fissure and is to be considered only as 

 a fluctuation between somewhat widely distant 

 extremes, which may even apparently include 



