76 PLANT LIFE. 



In other cases, proteids and carbohydrates are not 

 separated, and both occur in the same cell. Starch is 

 the most common of all the carbohydrates. It differs 

 frorp sugar, which is supposed to be the first carbo- 

 hydrate formed in the leaf, in its containing less water. 

 — (CgHigOe) sugar, and (CgHjoOg) starch. — The ripening 

 of the grain in the ear is, in fact, essentially a drying 

 process. The sugar travels to the grain and is there con- 

 verted by the protoplasm into starch. In spring, when the 

 seed germinates, this starch again becomes sugar, and as 

 such travels through the plant to any point where it is 

 required. The grains of starch are solid bodies formed 

 of a series of shells one outside the other, and varying 

 very greatly in shape and size. They are secreted by 

 the living protoplasm, of which part is generally 

 specialised for the purpose. Even in the structure of 

 these grains we find proof that living matter is not able 

 to go on working indefinitely. The shells above 

 described correspond to periods of rest and of working 

 quite similar to the waking and sleeping of animal life. 



In the Date and Vegetable-ivory seeds we find, instead 

 of starch, cell-wall substance ; the cell-walls of every 

 cell are very thick and hard, and are changed back 

 into sugar in spring. In this case the hardness, which 

 is a very marked character of both Vegetable-ivory and 

 the Date "stone," is clearly protective ; and the young 

 Palm, which may be noticed as a tiny white delicate 

 body halfway down the seed, is guarded against injury 

 by its own food. As these food reserves occur also 

 in stents^ rhizomes, bulbs, etc., these may for con- 

 venience be mentioned here. Cane sugar is found in the 

 Sugar Cane stem, the root of the Beet, and the young 

 stems of certain Palms. The trunk of the Canadian 

 Maple also contains a quantity of sugar, which is 



