8 PROOFS OF VITAL FORCE. 



This is shown, a, by the influence exercised over plants 

 by substances such as laudanum and arsenic ; h, by the active 

 and visible motions of the fluid contained within their cells ; 

 c, by the unerring directions taken by the delicate apparatus 

 which ensures reproduction by seed ; and d, by the locomotive 

 power possessed by the reproductive apparatus of the lower 

 classes of plants. 



M. It was long ago shown by Marcet, that if the common Kidney 

 Bean, the Lilac, and other plants, were exposed to the action of such 

 poisons as destroy animal life, they will perish not only under their 

 influence, but in a manner analogous to what occurs among animals. 

 If an animal is dosed with arsenic, or corrosive sublimate, or any 

 poisonous metallic salt, it perishes by inflammation or corrosion : plants 

 die in a similar way, their leaves turning yeUow and withering, no art 

 sufficing for their recovery. On the other hand, vegetable poisons 

 destroy life by a species of paralysis, leaves bending, and becoming 

 flaccid, and the whole plant rapidly falling into a state resembling 

 stupefaction, and ending in death. Every one knows that if the inner 

 face of the stamens of the common Berberry is touched they suddenly 

 rise upwards and dash their anthers against the stigma ; that after a 

 time they fall back, and then become able again to present the same 

 phenomenon. Macaire showed that when a twig of the Berberry in 

 flower is placed in weak Prussio acid, or a solution of opium, the stamens 

 lose their irritability, and become so flexible that they may be moved 

 backwards and forwards without difficulty. When, however, the 

 Berberry is placed in solutions of arsenic or corrosive sublimate, the 

 stamens equally lose their excitability, but instead of becoming flexible, 

 they are made stiflF, hard, and brittle. Similar efieots are produced 

 upon the Sensitive Plant and other species. Here we have direct 

 proof that the life of a plant is affected by destructive agents in the 

 same manner as animals. 



The curious effect of ansesthetic substances is the same upon plants 

 as on animals. Dr. Marcet has shown this by means of Chloroform. 

 "If," he says, "a drop or two of pure chloroform be placed on the 

 point of the common petiole of a leaf of the Sensitive Plant, the petiole 

 is soon seen to droop, and directly afterwards the leaflets collapse in 

 succession, pair by pair, beginning with those that are situate at the 

 extremity of each branch. A minute or two afterwards (the time vary- 

 ing with the irritability of the plant), most of the leaves near that on 

 which the chloroform was placed, and situate below it on the same 

 stem,, droop one after the other, and their leaflets collapse, althoun-h 

 not in so decided a manner as those of the leaf to which the chloroform 

 was applied. After a certain time, which vaaies with the condition of 



