20 



THE TLAXT. 



most clearly shown in the fourth stcage. The total weight 

 of leaves, which on the 1st September still amounted to 

 19,200 pounds, had by the 5th October, or within the 

 space of thirty-five days, decreased by 7,992 pounds, that 

 is 228 pounds a day ; in other words, out of every thirty- 

 four leaves ten had withered, while the roots had in- 

 creased by 22,392 pounds, or 640 pounds a day — a daily 

 increase much more considerable than during the third 

 stage. 



It is evident that with the advance of autumn, with the 

 lower temperature and diminished action of sunlight, the 

 organic energy of the leaves decreased, and more than a 

 third of the organisable matter collected in them de- 

 scended to the roots, to be stored up for future use. 



If we compare the quantities of nitrogen, phosphoric 

 acid, potash, common salt, and sulphuric acid, absorbed 

 during the last ninety days by the turnips growing on 

 one acre of ground, we find from Anderson's experiments 

 that the daily amount was as follows : — 



Absorbed by the entire plcmt in a day. 



Daily inc7-ease of roots in. the fourth stage of groivth. 



