618 Mutations 



seedlings of the typical species in a single in- 

 dividual. This was transplanted into the Jar- 

 din des Plantes at Paris, where it flowered and 

 bore seeds in 1865. It must have been partly 

 pollinated by the surrounding normal repre- 

 sentatives of the species, since the seeds yielded 

 only one-fourth of true offspring. This propor- 

 tion, however, has varied in succeeding years. 

 Briot remarks that the monophyllous bastard- 

 acacia is liable to petaloid alterations of its 

 stamens, which deficiency may encroach upon 

 its fertility and accordingly upon the purity of 

 its offspring. 



Broom-like varieties often occur among trees, 

 and some are known for their very striking re- 

 versions by buds, as we have seen on a previous 

 occasion. They are ordinarily called pyramidal 

 or fastigiate forms, and as far as their history 

 goes, they arise suddenly in large sowings 

 of the normal species. The fastigiate birch was 

 produced in this way by Baumann, the Abies 

 concolor fastigiata by Thibault and Keteleer at 

 Paris, the pyramidal cedar by Paillat, the analo- 

 gous form of W ellingtonia by Otin. Other in- 

 stances could easily be added, though of course 

 some of the most highly prized broom-like trees 

 are so old that nothing is known about their 

 origin. This, for instance, is the case with the 

 pyramidal yew-tree, Taxus haccata fastigiata. 



