the 



of these nuclei is uncertain ; it is probable that 

 they are connected with the power, which the cuticle of 

 these plants possesses, of preventing the evaporation of 

 their internal moisture in times of drought. 



common European 



An interesting fact relating to the 



" Among the 



Opuntia is mentioned by M. De Candolle. 

 practical consequences," he observes, " that result from the 

 facility with which Cacti strike from cuttings, there is one 

 which deserves to be noticed, on account of its importance : 

 it is, the manner in which the Opuntia is employed to fertilise 

 the old lavas at the foot of Etna. As soon as a fissure is 

 perceived, a branch or joint of an Opuntia is stuck in ; the 

 latter pushes out roots, which are nourished by the rain 

 that collects round them, or by whatever dust or remains 

 of organic matter may have collected into a little soil; 

 these roots, once developed, insinuate themselves into the 

 most minute crevices, expand, and finally break up the lava 

 into mere fragments. Opuntias treated in this manner pro- 

 duce a great deal of fruit, which is sold as a refreshing food 

 throughout all the towns of Sicily." 



J. L. 



