93 



by combining more molecules of water (H 2 -0) it becomes 

 C 6 H 12 0 6 grape sugar and fruit sugar, or else C 12 H 22 0 1:L 

 (cane sugar). In this state it is transmissible and con- 

 veyed to all growing parts, where it is the material for making 

 cellulose, which has the same constitution as starch (C 6 H 10 0 5 ). 

 Indeed, several other substances are of precisely the same propor- 

 tions, such as gum, dextrin, mucilage, etc. As they all have the 

 same substances, carbon and water, they are called carbo- 

 hydrates. Many other carbonaceous products occur in plants, 

 but the elements are in different proportions ; thus, the outer 

 portion of the cell-wall of the epidermis is called the cuticle. This 

 has the following proportions: — C, 73.66, H, 11.37, an d O, 14.97. 

 There is another in cork, C, 74, H, 10, O, 16. Then there are 

 several kinds of oil as in nuts and olives, with similar high propor- 

 tions of carbon, hydrogen, and oxygen. These all have their uses 

 in plant life; thus, while starch is the commonest food for the 

 embryo to germinate upon, as in wheat, in kernels of nuts and 

 almonds it is oil. 



The only living substance, protoplasm, has been alluded *.o. 

 This carries the life of the plant. It is found in all growing and 

 living cells. Its composition consists of carbon, hydrogen, nitro- 

 gen, oxygen, sulphur, and phosphorus ; but these elements are in 

 such high proportions that it has never been accurately analysed. 

 One of the nearest approaches to it is albumen forming the white 

 of an egg ; and as several nitrogenous products of plant-1'fe 

 approximate to this they are called albuminoids. These are the 

 substances which renew the protoplasm and supply food for the 

 new cells as they are continually being increased in number. Like 

 starch and oil, as well as other things without nitrogen, albumin- 

 oids are stored up as reserve food for future use. Starch is the 

 chief thing in potatoes, which give rise to new plants ; while sugar 

 is found in turnips, beetroot, carrots, etc., for the second year's 

 flowering process ; whereas, both starch and albuminoids are 

 found in considerable quantities in seeds for the germ or embryo 

 to live upon until it has developed roots and leaves. 



Similarly as the animal kingdom lives upon the vegetable, 

 these same substances constitute its food also, for the analysis of 

 animal and vegetable protoplasm is practically the same. 



As an example let us take a grain of wheat. This is a seed 

 invested by the carpel as forming an extra coat. As this consists 

 of three layers of cells, while the seed itself has two, the wheat- 

 husk consists of five. Excepting two layers, they are useless (that 

 is, as food for the embryo), but the late Sir A. H. Church dis- 

 covered that they contain certain salts which are beneficially 

 added to the food proper. 



The outermost layer of the internal food-substance, called 

 the endosperm by botanists, and forming flour when ground, 

 consists of cells filled with the reserve albuminoids. It is called 

 the " cerealin " layer, and is the part which is of the greatest 

 importance. For all the rest, excepting the germ or embryo, 



