THE LOWER FORMS OF LIFE. 



division known to the highest power of our microscopes. How this 

 pollen grain gets into the seed I will show by and by. But the 

 embryo now must be considered as an aggregate of four protophytic 

 cells, containing an albuminous or nitrogenous fluid (similar some- 

 what in its properties to white of egg), molecular matter, and a 

 nucleus. Now, each of the four cells, the embryo cotyledon, 

 plumule, caulicle, and radicle (Fig. 2, p. 3), multiply, and so each 

 organ grows. But this growth requires new matter to be supplied, 

 so that the vital powers of the cell can then form new material. In 

 other words, the young cells require feeding. Helpless as a new- 

 born babe without a mother would be that young embyro plant 

 unless wise forethought had made provision to meet its necessities. 

 As yet, the young plant cannot help itself. Its roots and leaves are 

 unformed. Just, however, as milk is provided for a helpless babe, 

 so is food provided for the helpless plant. That food is the flour 

 which, when the seed is ground, makes our bread. It is the 

 albumen of the seed (/, Fig. 2, p. 3). But the plant, whether in its 

 embryonic or matured condition, can only take in food in a fluid 

 or aerial condition. Now, the flour of the wheat-seed is not easily 

 soluble, at least, not so as to be taken up by a tender organism like 

 our wheat-plant. How is this difficulty overcome ? 



Nothing in nature is more striking and beautiful than the answer 

 to this question. If the flour of the wheat-seed were more soluble 

 it would be spoiled when subjected to wet ; it would not keep in our 

 granaries, and its use as human food would be lost to mankind. 

 When subjected, however, to moisture, heat, and atmospheric air, 

 the flour is chemically decomposed, and the starch which it contains 

 is converted into sugar, which is soluble, and in that condition can 

 be taken up as food by the embryonic plant. To understand this 

 clearly, a word or two must be said about the chemical constitution 

 of a grain of wheat. 



It consists of organic or vegetable, and inorganic or mineral sub- 

 stances. The vegetable are starch and gluten ; the mineral, phos- 

 phorus, lime, iron, magnesium, sodium, potassium, silica, and 

 sulphur. There are also certain gases chlorine, oxygen, carbon, 

 hydrogen, and nitrogen. 



To avoid confusing the non-chemical reader, I will confine myself 

 for the present to the chemistry of the change which is undergone 

 by the flour of the grain during germination. 



Starch, of which the best wheat-flour contains from 60 to 66 per 

 cent., is thus composed in atoms : 



Carbon. Hydrogen. Oxygen. 



Starch 12 10 10 



Grape sugar is composed of 12 14 14 



