48 THE PLAtfT. 



period goes to the roots, and that this store is after- 

 wards applied to the formation of the stalk. On the 

 approach of warmer weather all the operations of life in 

 cereal plants are quickened, and the quantity of food 

 daily absorbed and worked up increases with the extent 

 of the absorbing and elaborating organs. In spring 

 many of the older leaves and of the root-fibres die in 

 the portions of the soil exhausted by them ; the root- 

 tops send forth new buds, and with every new bud new 

 rootlets, until the stalk-joints have attained a certain 

 length. From this time forward to the end of the pe- 

 riod 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 2J 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 win- 

 ter, which puts a certain limit to the activity of the 

 outer organs, without altogether suppressing it, is essen- 

 tial to the vigorous thriving of winter corn. It is a 

 most favourable condition for future developement, if 

 the temperature 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 un- 

 favourably upon the future crop, as the higher temper- 

 ature encourages the developement of the principal 

 stalk before the proper time, which shoots up thin, and 



