340 GANGRENE OF PLANTS. 



French islands. Such were the siiplnene.stt 

 and ignorance of the Spaniards, that he suc- 

 ceeded in conveying, not only the living in- 

 sects, but the bullvy plant necessary for their 

 sustenance, notwithstanding severe edicts to 

 the contrary. He had attended previously to 

 the management of the Nopal, and made his 

 •remarks on the diseases to which it is' liable. 

 Of these the Gangrene is extremely frequent 

 in the true Nopal of Mexico, beginning by a 

 black spot, which spreads till the whole leaf 

 or branch rots off, or the shrub dies. But 

 the same kind of plant is often affected with 

 a much more serious disease, called b}'^ Thiery 

 *' la dissolution." This seems to be a sudden 

 decay of the viteil principle, like that pro- 

 duced in animals by lightning or strong elec- 

 tricity. In an hour's time, from some un- 

 known cause, a joint, a whole branch, or 

 sometimes an entire plant of the Nopal, 

 changes from apparent health to a state of 

 putrefaction or dissolution. One minute its 

 surface is verdant and shinino' ; the next it 

 turns 3'ellow^, and all its brilliancy is gone. 

 On cutting into its substance, the inside is 

 f©und to have lost all cohesion, being quite 



