36 



THE PLANT. 



light, the organic energy of the leaves decreased, and 

 more than a third of the organisable matter collected in 

 them descended 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 experi- 

 ments that the daily amount was as follows : 



Absorbed by the entire plant in a day. 



Daily increase of roots in the fourth stage of growth. 



These figures show that the quantity of phosphoric 

 acid taken up daily by the turnip plants growing on 

 one acre of ground increases from the commencement 

 of the second to the end of the fourth stage of growth, 

 that is in ninety days from 0*924 to 1*25 pound a-day, 

 which reckoned from one day to another makes the 

 trifling difference of 0*0037 pound a-day. 



Anderson suspects that his estimate of the nitrogen 

 in the leaves during the third stage was not quite cor- 

 rect, and that it fell below the actual amount. If we 



