GROWTH OF TUENirS. 19 



in the leaves, and 2,755 poiintls in the roots, wliicli gives 

 a daily increase of 



Loaves Eoots 



359 pounds I 78 pounds 



In this stage, accordingly, the production of leaves 

 prevailed over that of roots to this extent, that out of 

 eleven parts of food absorbed by the plants, nine parts 

 went to the leaves and only two parts to the roots. 



We find a very different proportion in the third stage ; 

 for during twenty days the weight of the leaves has 

 increased by 6,507 pounds, that of the roots by 11,638 

 poimds, which gives a daily increase of 



Leaves Roots 



325 pounds | 582 pounds 



During this third stage the plants take up daily somewliat 

 more than double the amount of food taken up on any 

 given day of the second stage, and this increase must 

 stand in proportion to the daily enlargement of the surface 

 of the roots and leaves ; but the food absorbed is dis- 

 tributed in the plant in a very different manner. Of 

 twenty-five parts by weight of food absorbed and as- 

 similated, nine parts only remain in the leaves, the other 

 sixteen parts serve to increase the mass of roots. 



In exactly the same ratio as the leaves approached the 

 limits of their developement, they lost the power of ap- 

 plying to their further growth the food which tliey had 

 absorbed, and which now transformed into organisable 

 matter was deposited in the roots. The same nutritive 

 particles which went to form leaves, so long as the mass 

 of foliage kept on increasing, now became constituent 

 portions of the root. 



This migration of the constituents of the leaves and 

 transformation into constituents of the root ap])ear to be 



