FREAKS OF PLANT LIFE. 239 



CHAPTER XI. 



SLEEP OF PLANTS. 



As long ago as the time of Pliny, nearly two 

 thousand years, certain appearances in plants were 

 observed, which seemed to indicate a condition of 

 repose, as exhibited in the phenomena since desig- 

 nated as the "sleep of plants." The celebrated 

 Linnaeus devoted an essay to this subject, and it has 

 since been made the theme of various -authors. By 

 the " sleep of plants," is generally included such 

 movements of the leaves as take place periodically 

 towards the close of the day, and which consist in 

 moving upwards or downwards into such a position 

 that the blade of the leaf shall be vertical or nearly 

 so. There is no real analogy between the sleep of' 

 animals and the sleep of plants, and the latter term 

 must therefore be accepted rather as a poetic simile, 

 than as a record of fact. The term " nyctitropism " 

 has been proposed as a less objectionable synonym, 

 but its use will scarcely be necessary here, since the 

 more popular term is not liable to be misapplied. 



" The fact that the leaves of many plants place 

 themselves at night in widely-different positions from 



