296 THE DISCOVERY OF PLANT SLEEP. 



been disproved by the experiments of the elder De 

 Candolle, the great Swiss botanist, who found that they 

 were exhibited by plants enclosed in hot-houses where 

 the temperature was constantly maintained at a fixed 

 point, showing that these movements were due, not to 

 cold, but to the abstraction of light* they went to sleep 

 in fact, much as the birds do, as Linnaeus had said, 

 upon the approach of night. 



Louis Figuier, a learned French physician, only 

 lately deceased, has given some interesting details upon 

 this subject in his "Histoire des Plantes," and tells 

 us that when the sleep of plants was first discovered, 

 and when Linnaeus saw " that this phenomenon could 

 hardly be confined to a single plant" (such as the 

 Lotus then under his observation) but must be " general 

 throughout the vegetable kingdom" he forthwith 

 devoted his nights to the study of this question, with 

 the result that " at every step he discovered fresh facts" 

 in support of his supposition ; respecting w r hich, as Mon- 

 sieur Figuier remarks, it may be asserted that "no 

 natural fact once brought into notice has been so 

 rapidly established by a host of confirmatory evidence" 

 as was this curious function of sleep among the members 

 of the vegetable creation, y Remarkable also is the 

 additional circumstance first brought to light by De 

 Candolle, that precisely as in the case of the young of 

 both man and animals, to whom the amount of sleep 

 necessary in infancy is greatly in excess of that required 

 by adults, so also with young plants this phenomenon is 



* See collection of reports to the " Institut National " of France, in 

 the British Museum, " fait par les citoyens Thouin et Desfontaines sur 

 un memoire intitule ' Experiences relative a V influence de la lumiere 

 sur quelques vegetaux par le citoyen Decandotte.' " 



f Histoire des Plantes, by Louis Figuier, Paris 1865, pp. 109 112. 



