32 SAGACITY AND MORALITY OF PLANTS. 



carbon, oxygen, hydrogen, nitrogen, sulphur, and 

 phosphorus. These form a sort of committee, with 

 power to add to their number. Consequently, when 

 any other element is required by protoplasm — such 

 as soda, potash, lime, magnesia, etc. — it is at once 

 enlisted. This protoplasm is to the cells of a plant 

 what the prepared clay of the brickmaker is to the 

 bricks formed of it. In the construction of the walls 

 of cells, however, considerable economy is exercised — 

 only carbon, oxygen, and hydrogen being employed. 

 Hence the composition and identity in the structure 

 of the cell -walls of all kinds of plants contrasts 

 singularly with the variety of the chemical contents 

 of the cells. The albuminoid substances of plants, 

 although they assume a good many shapes, are 

 chemically very much alike, their nitrogen being to 

 animals, perhaps, their most important constituent. 

 These are usually most abundantly present in the 

 growing parts of plants. 



Thus far I have been concerned with sketching 

 the vegetative life of plants, and the structures which 

 carry on the work. Now let us turn to the not less 

 important structures and functions of reproduction. 

 The former are best known to us in the shapes of 

 flowers and fruits. 



The chief, nay, the only necessary organs of a 

 flower, are the pistil and stamens. All the rest of 

 floral organs are simply auxiliaries, called in to 

 assist when necessary, but not unfrequently dispensed 



