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plants, — particularly with regard to the flow of sap. 

 This he ascribed to a sort of galvanism, or intra- 

 capillary electricity; to the two currents of which, or, 

 more properly, to the motions produced by them, he 

 gave the melodious epithets of endosmose and exos- 

 mose. His experiments and his reasonings were, 

 however, afterwards shown to be fallacious; and, with 

 a degree of candor and love of truth, more honora- 

 ble to him than many golden medals, he retracted his 

 opinions. 



Another gentleman has still more recently come 

 forth with the publication of a series of experiments 

 and inferences, which are said to prove satisfactorily, 

 at least to himself, that caloric^ in its annual and di- 

 urnal fluctuations, is alone the cause of movement in 

 the sap. It were well, perhaps, if both these gentle- 

 men had been satisfied with attributing the phenom- 

 enon to an inherent vital action, without puzzling 

 themselves with a vain search after first causes, — 

 which always leaves the most successful inquirer ex- 

 actly where he set out. 



Although observation is the faculty principally em- 

 ployed in the study of Natural History, and should 

 always be on the alert to surprise Nature in the 

 midst of her operations, and thus detect her secrets ; 

 yet, in some cases, and to a limited extent, experi- 

 ment may be employed to extort them from her. 

 But the Naturalist cannot, like the Chemist, regulate 

 the conditions of the phenomena he studies ; nor can 

 he separate the elementary parts from each other, in 

 the objects he examines. Such objects usually come 

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