OF WHAT A SEED CONSISTS. 259 



consequently cannot explain, as we can the converse change 

 of woody fiber into starch and starch into sugar. 



The term seed is agricultural, botanically the seed is the 

 fruit; and what is commonly called a fruit is the recepta- 

 cle of the seed. Thus a melon or an apple is thef receptacle 

 in which the seeds and fruit are contained; a strawberry is 

 a flephy receptacle upon which the fruit or seeds are im- 

 planted. Here however the popular meaning is given to 

 these terms and fruits and seeds are understood in the com- 

 mon use of the words. 



The seeds of a plant, as we have seen, consist of a mass of 

 starch cells enclosed in a husk, and in which is imbedded 

 the germ with its nitrogenous gluten surrounding it. These 

 starch cells are enclosed in several envelopes; a grain of 

 wheat having three distinct coats differing in character; the 

 inner ones containing potash, gluten, and phosphoric acid, 

 in larger proportion than any other part of the seed. Some 

 of the grains have husks which contain a large quantity of 

 silica; oats for instance having 46 per cent, of silica in the 

 ash; and the ash of millet containing 52 \ per cent, of this 

 mineral. 



During the process of ripening of the seed this excessive 

 deposit of silica is most remarkable in the stem. As an 

 important function of the stem is the support of the seeds, 

 this deposit of silica in it is necessary to strengthen it and 

 enable it to sustain the comparatively heavy weight of the 

 seeds. But this large deposit of earthy matter is an im- 

 portant consideration to the farmer whose business it is to 

 produce as much nutriment in his fodder crops for the sub- 

 sistence of his animals as he can, and as silica is of no use 

 in the alimentation of animals, its presence in the fodder is 

 not desirable. 



Young grass contains only as much silica as makes up 

 10.3 per cent, of its ash; while the ash of the ripened hay 

 has 63 per cent, of it; the potash in it amounts to only 7 

 per cent, against 56 per cent, in the ash of the young grass. 

 This change in the composition of vegetable tissue affects 

 all plants; for as the starch and gluten are stored up in the 



