92 EXPERIMENTAL EVOLUTION LECT. 



Similar cases are met with among spiny plants. 

 While some plants, which possess no spines, become 

 markedly spiny when they grow in some localities, 

 others, which are spiny, lose their appendages. Such 

 is the case with Capparis spinosa for instance, of which 

 Turrel l has described a variety without spines in the 

 Balearic Islands. In all other respects this variety 

 exactly resembles the common form. Whether a 

 lusus naturae or not, this peculiar character is heredi- 

 tary, as the seeds of this form always yield non-spiny 

 plants, in France as well as at Mahon. Another case 

 is that of Ulex europaeus, of which there exists a non- 

 spiny form, as Trochu has shown. 2 This form is 

 seldom met with, as it has less chances of success in 

 the struggle for life, for while oxen, rabbits, hares, 

 and other animals are respectful and deferential 

 towards the common spiny form, they have a great 

 liking for the other one, and eat all they can of it. It 

 must be added also that the last-named bears but 

 few seeds, and thus cannot become very abundant. 

 De Jussieu considers this Ulex nanus as a variety of 

 Ulex europaeus, and Vilmorin has made some in- 

 vestigations concerning this form, 3 which may become 



1 L, Turrel : Sur le Caprier sans Epines. Bull. Soc. Zool. Acclima- 

 tation, vol. viii. p. 448. 



2 L. Vilmorin : De PAjonc sans Epines. Revue Horticole, vol. xii. 

 p. 151. 



3 Note sur un projet d? Experience ayant pour but de creer line Variete 



