GROWTH OF PLANTS. 305 



as a tree, as it is actually the case in the polar regions, where 

 one long day and night comprise the year. If on the other 

 hand, they grow in constant darkness, their tissue becomes 

 excessively lengthened and weak; no decomposition of car- 

 bonic acid takes place; none of the other parts acquire solidi- 

 'ty and vigor; and finally, they perish. But under the beautiful 

 arrangement of Providence, plants which in the day become 

 exhausted by the decomposition of carbonic acid, and by eva- 

 poration, repair their strength at night, by inhaling oxygen 

 copiously, and so forming a new supply of carbonic acid, 

 by absorbing moisture from the earth and air without losing 

 any portion of it.* 



I suppose that the reason that fruits are more acid in the 

 morning than in the eveningf is, that in the sun's rays, they 

 decompose their carbonic acid, and part with their oxygen, of 

 which they do not gain a fresh supply until night. 



MRS. F. 



It is so. Botanists have also found that leaves which are 

 acid in the morning, and will turn litmus paper:}: red, pro- 

 duce no effect upon it by noon, and are then tasteless. Starch, 

 again, in which carbon forms- so large a proportion, and which 

 in the potato, cassada, corn, beans, peas, &c., contributes so 

 largely to the nourishment of man, depends for its abundance 

 essentially upon the presence of light. It also increases the 

 saccharine matter in the sugar-cane, and completes the forma- 

 tion of oil in the seeds of oleaginous plants. 



ESTHER. 



Mr. Knight, the President of the Horticultural Society, has 

 turned this known fact to great account in the cultivation of 

 potatoes. He leaves wide intervals between his rows, and 

 makes them lie from north to south, so as to expose as large 



* Lindley. t Ibid. J See Chapter XI. 



26* 



