EXCESS OF NUTRIMENT. 



microscope. The barks of several aspens and pine-trees* con- 

 tain so much substance, that it can be extracted from them as 

 from potatoes by trituration with water. It exists also in the 

 roots and other parts of perennial plants. A very early winter, 

 or sudden change of temperature, prevents the formation of 

 this provision for the following year ; the wood, as in the case of 

 the vine-stock, does not ripen, and its growth is in the next year 

 very limited. 



From the starch thus accumulated, sugar and gum are pro- 

 duced in the succeeding spring, while from these the unnitrogen- 

 ized constituents of the leaves and young sprouts are in their turn 

 formed. After potatoes have germinated, the quantity of starch 

 in them is found to be diminished. The juice of the maple-tree 

 loses sugar and ceases to be sweet, when its buds, blossoms, and 

 leaves attain their maturity. 



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 or rain-water ; but in 

 proportion as it grows, the starch disappears, it being evidently 

 exhausted for the formation of the roots and leaves. 



Upon the blossoming of the sugar-cane, likewise, 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. 



These well-authenticated observations remove every doubt as 

 to the functions performed by sugar, starch, and gum, in the de- 

 velopment of plants ; and it ceases to be enigmatical, why these 

 three substances exercise no influence on the growth or process 

 of nutrition of a matured plant, when applied to it as food. 



The accumulation of starch in plants during the autumn has 

 been compared, although certainly erroneously, to the fattening 

 of hibernating animals before their winter sleep ; but in these 

 animals every vital function, except the process of respiration, is 

 suspended, and they only require, like a lamp slowly burning, a 

 substance rich in carbon and hydrogen to support the process of 

 combustion in the lungs. On their awaking from their torpor in 



* It is well known that bread is made from the bark of pines in Sweden 

 daring famines. 



