MEMOIR 01 PYRAMUS DE CANDOLLE. 273 



would you charge yourself with that labor?" Startled at this unex- 

 pected proposition, the youth would have excused himself, as well on 

 account of the difficulty of the subject as his own defect of Knowledge. 

 " Yon will see," said the good Desfontaines, " that it is not as difficult 

 as you imagine; come and work at my house; I will direct you." 



The- reputation of De Candolle commenced at twenty years of age 

 with the Histoire des Plantes Grasses. But shortly a labor of a higher 

 and more original character designated more clearly the rank which 

 he was to take in science. He had fortunately conceived the idea 

 of occupying himself with the sleep of plants. 



The first step was to assure himself that air goes for nothing in 

 this phenomenon; for plants which sleep, when immersed in water, 

 pass as usual from sleep to waking and from waking to sleep. Setting 

 aside, then, the action of air, there remained that of light. The plants, 

 therefore, were placed in darkness, and alternately exposed to its in- 

 fluence and to that of light. By illuminating these plants during the 

 night, and leaving them in obscurity during the day, De Candolle suc- 

 ceeded in completely changing the hours of their waking and sleeping; 

 he saw the nocturnal plants open in the morning, and the diurnal in 

 the evening. 



These curious experiments, being communicated to the Academy, 

 excited the most lively interest; and, indeed, the results obtained bv 

 the author may be said, without exaggeration, to have possessed 

 something of the marvellous, even for the vulgar. By the aid of arti- 

 ficial light alone he had colored etiolated plants green;* had changed 

 the hours of sleep and waking; and had proved the remarkable fact 

 that plants hare habits; for it is not all at once, but only at the end 

 of a certaiu time, that they discard their ordinary hours and adopt 

 others. Thus the life of plants is shown to be a more complicated 

 phenomenon, and one much more nearly approaching that of animals 

 than had been yet suspected. They have their activity and repose, 

 their sleep and waking, and likewise their habits; so that when De- 

 lille, celebrating these results in verse, proceeds to say, 



The calyx of the credulous flower is duped ; 



we feel that poetry ; in view of such facts, has almost lost the privi- 

 lege of being metaphorical. 



Fontenelle has remarked "that botany is no sedentary and slothful 

 science which may be acquired in the repose and shade of the closet; 

 it demands that its votary should traverse mountains and forests, 

 climb the acclivities of rocks, and expose himself on the edge of 

 precipices." Applied in the first instance to Tournefort, these ex- 

 pressions would have been doubtless thought by their author equally 

 applicable to De Candolle. The Flore Fraticaise, the flora of that 

 vast empire which was every day extending its frontiers by victory, 

 furnished him with the occasion for many fatiguing expeditions. His 



° It is necessary to remark, however, that the coloration was imperfect — the plants, as 

 he himself said, rureaining intermediary between etiolated and green ; nor had the arti- 

 ficial light, which he employed, sufficient intensity to develop oxygen gas. M. Humboldt 

 had already observed the same phenomenon : Comptes rendus de l Academie, Tome XV, p. 

 1194 — Author. 



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