BOTANY. 205 



Carbonic acid, azote, and some other gases, have 

 proportionate effects. 



Minimum of Temperature. 



In Europe, it is observed that the minimum of the 

 mean temperature which a proper cultivation re- 

 quires, is : 



For the Sugar-cane, from 66 to 68 Fahrenheit. 



Coffee 64 



Orange 62 



Olive ... 56 to 57 

 Vine yielding 1 



\vine fit to be drank J 



The white birch-tree is found nearer the pole, and 

 on more elevated situations, than pines, firs, or any 

 other tree. 



The heat of plants, in many instances, is above 

 that of the surrounding medium. 



The Sleep of Plants. 



The common chickweed, with white blossoms, 

 affords a notable instance of what is called the sleep 

 of plants; for every night the leaves approach in 

 pairs, so as to include within their upper surface the 

 tender rudiments of the new shoots, while the upper- 

 most pair but one at the end of the stalk are fur- 

 nished with longer leaf-stalks than the others, so that 

 they close on the terminating pair, and protect the 

 end of the branch. 



Efflorescence. 



The earliest periods of the efflorescence of the 

 following flowers, in lat. 53 30', (nearly that of 

 Manchester,) are the following, viz. 



January. 



14th. Ulex Europaeas the common furze. 

 16th. Bellis perennis the common daisy. 



