IV.] 



BOTANY. 



the cells of a walnut leaf (Fig. 7), and in rhubarb 

 (Fig. 8), and beet (Fig. 9). 



FIG. 7. FIG. 8. FIG. 9. 



Crystals of oxalate of lime, as found in cells, many times the real size. 



23. The great importance of the nitrogenous sub- 

 stance protoplasm, as the only living matter which the 

 plant contains, cannot be too firmly insisted upon. 

 It is of the same nature as the protoplasm of which 

 some of the lowest animals (those nearest the plants) 

 wholly consist, and which forms the living substance 

 of the bodies of the higher animals, including man 

 himself. 



Like animals, plants cannot live without oxygen. 

 The activity of the protoplasm in both cannot be kept 

 up without it. The protoplasm of all living things 

 wastes and would die altogether unless it were 

 nourished. This process of nourishing involves 

 respiration, i.e. getting rid of superfluous carbon, 

 which combines with oxygen taken in from the air, 

 and is given off as carbonic acid (Par. 158). 



