34 THE PLANT. 



joints have attained a certain length. From this time 

 forward to the end of the period of vegetation, both the 

 food absorbed by the plant, and the movable part of the 

 materials formed in the leaves, stem, and root, go to form 

 flowers and seeds. 



The observations of Schubart show that the roots of 

 cereal plants, in the first period of vegetation, increase 

 much more than the leaves. Schubart found that rye 

 plants, which, six weeks after sowing, presented leaves 

 5 inches long, had meanwhile produced roots 2 feet in 

 length. 



The vigour with which cereal plants send forth their 

 stalks and side-shoots corresponds to the developement of 

 the root. Schubart found as many as eleven side-shoots 

 in rye plants, with roots 3 to 4 feet long ; in others, where 

 the roots measured If to 2^ feet, he found only one or 

 two ; and in some, where the roots were but 1^ foot, no 

 side-shoots at all. 



The action of a low temperature in autumn and winter, 

 which puts a certain limit to the activity of the outer 

 organs, without altogether suppressing it, is essential to 

 the vigorous thriving of winter corn. It is a most 

 favourable condition for future developement, if the tem- 

 perature of the air is below that of the soil, so as to retard 

 for several months the developement of the outer plant. 



Hence a very mild autumn or winter operates unfavour- 

 ably upon the future crop, as the higher temperature en- 

 courao-es the developement of the principal stalk before the 

 proper time, which shoots up thin, and consumes the food 

 which should have served to form buds and new roots, or 

 to increase the store of organisable matter in the roots. 

 Thus stunted in its developement, the root supphes less food 

 to the plant in spring, as it takes up and gives out less in 

 proportion to its smaller absorbent surface and more 



