NUTRITION AND GROWTH OF PLANTS. 125 



The branch of a willow, which contains a large 

 quantity of granules of starch in every part of its 

 woody substance, puts forth both roots and leaves 

 in pure distilled rain-water ; but in proportion 

 as it grows, the starch disappears, it being evidently 

 exhausted for the formation of the roots and leaves. 

 In the course of these experiments, M. Heyer made 

 the interesting observation, that such branches 

 when placed in snow-water (which contains ammo- 

 nia) produced roots three or four times longer than 

 those which they formed in pure distilled water, 

 and that this pure water remained clear, while the 

 rain-water gradually acquired a yellow colour. 



Upon the blossoming of the sugar-cane, like- 

 wise, part of the sugar disappears ; and it has been 

 ascertained, that the sugar does not accumulate in 

 the beet-root until after the leaves are completely 

 formed. 



Much attention has recently been drawn to the 

 fact that the produce of potatoes may be much 

 increased by plucking off the blossoms from the 

 plants producing them, a result quite consistent 

 with theory. This important observation has been 

 completely confirmed by M. Zeller, the director of 

 the Agricultural Society at Darmstadt. In the year 

 1839 two fields of the same size, lying side by side 

 and manured in the same manner, were planted 

 with potatoes. When the plants had flowered, the 

 blossoms were removed from those in one field, 

 while those in the other field were left untouched. 



