Vegetative Mutatiuns. 



C)29 



to obtain any seed (Fig. 137, p. 61S), l)ccaiise it ilnu- 

 ered too late in the year. I have cultivated this plant, 

 which was descril^ed and figured in the first section of 

 this volume (p. 92), for many years by vegetative meth- 

 ods, because it is perfectly sterile. In the summer of 

 1902, however, it suddenly began to produce bud-varia- 



Fig. 143. Carpinus Betulus. At a. a partly variegated leaf 

 on a tree which had otherwise only green leaves, Ililvcr- 

 sum (1887). 



tions. distributed in considerable numbers over the various 

 main stems; they were apparently independent n{ one 

 another, but seemed to arise in response to the same un- 

 known external influences. The fiowerheads of the ata- 

 vistic branches were of the normal structure of the ordi- 

 nary Dahlias, double, and with carmine red florets, at the 

 tip of each of whicli was a white spot. From this we 



