344 CULTIVATION OF GRASSES, 



stems have no bark ; but these tall and slender stalks de- 

 rive their stability from a quantity of silex, which, not be- 

 ing of a volatile nature, is deposited on the surface of the 

 straw or culm, when the more volatile parts evaporate. 

 Here it accumulates, and in the course of time incloses 

 the straw in a species of coat of mail, which not only ena- 

 bles it to resist injury, but also to support the weight of 

 seed it has to bear. 



Emily. Were it not for this provident supply of Nature, 

 it is true that a slender hollow straw would be quite un- 

 equal to support the burden of a heavy ear of corn. 



Mrs. B. In this and all northern countries, the straw 

 is generally hollow, but in warm climates it is full. The 

 stems of gramineous plants are also intersected with knots 

 or articulations, designed, no doubt, to add to its strength ; 

 and each of these, shoots out a long slender leaf, which 

 encloses the stem like a sheath. 



Grain constitutes the fruit of corn, and consists, conse- 

 quently, of the seed and its pericarp : these are so closely 

 attached together that they are not easily separated or 

 distinguished from each other, when in the state of grain : 

 but when ground into flour, it is the pericarp which forms 

 the coarse bran ; and the seed, the flour used for common 

 household bread. 



Emily. This flour then consists of the contents of the 

 seed together wirh its spermoderm : and it is, no doubt, 

 the latter which renders it brown ? 



Mrs. B. You are right ; in order to obtain the whitest 

 wheaten flour, such as the bread in London is made of, 

 the spermoderm, which forms a finer species of bran, must 

 also be subtracted : all this is very adroitly performed by 

 that skilful naturalist the miller, with his sieve of moulting 

 cloth. 



Emily. How admirably this seed is protected ! it is true 

 that it is one of great importance to mankind : but is it not 

 curious to think that so small a body as a grain of corn 

 should have two coverings, consisting each of three coats ? 



Caroline. And the husk, besides, for an outer garment. 

 I thought it had been the husk which formed the bran. 



1861. From what do the stalks of corn derive their stability 1 ? 

 How does the straw, as to solidity, vary in different climates'? 1863. 

 Of what does grain consist 1 ? 1864. What parts form the coarse 

 bran, and what the flour 1 1865. How is the finest wheaten flour ob- 

 tained 1 ? 



