264: THE WONDERS OF VEGETATION. 



it is often difficult to recognize them in their strange 

 disguise. 



This condition is what Linnaeus, who discovered it 

 m Sweden, terms the sleep of the plants, although 

 this expression, borrowed from animal life, and ap- 

 plied to plants, does not mean the same thing as with 

 animals a state of repose and flaccidity ; for during 

 the night, plants are as stiff and firm as they are dur- 

 ing the day. Linnaeus, in order to verify the differ- 

 ence in the condition of leaves during the day 

 and the night, used to deprive himself of sleep, for 

 several nights, and descend into his garden to exam- 

 ( ine his plants. He soon discovered that it was the 

 absence of light only, and not the intensity of cold, 

 to which this phenomena was chiefly due ; and this 

 fact was of use to him in establishing upon better au- 

 thority than heretofore the connection that subsists 

 between light and the organization of plants. He 

 next carried some of them into green-houses, where 

 they were protected from all injurious influences, and 

 ascertained that even thus sheltered, the plants yielded 

 as submissively to the negative influence of darkness 

 as their companions in the open air. He also found 

 out that the difference between night and day is 

 much more keenly felt by young than by old plants ; 

 and constant observation proved to him that the ob- 

 ject of nature in establishing this difference, was to 

 provide for the early closing of the young and ten- 

 der leaves, which are more sensitive than those of 

 older growth to the influence of cold and the night 

 air. 



