

COMPOSITION OF LIVING THINGS 33 



ical elements must enter into the composition of the food sub- 

 stances as are found in living matter. The simplest plants and 

 animals have this wonderful power as certainly developed as the 

 most complex forms of life. 



(5) Protoplasm, be it in the body of a plant or of an animal, uses 

 oxygen. It breathes. Thus substances taken into the body are 

 oxidized, and release energy for movement and the other activi- 

 ties of plants and animals. 



(6) Protoplasm has the power to rid itself of waste materials, 

 especially those which might be harmful to it. A tree sheds its 

 leaves, and as a result gets rid of the accumulation of mineral matter 

 in the leaves. Plants and animals alike pass off the carbon dioxide 

 which results from the very processes of living, the oxidation of 

 parts of their own bodies. Animals eliminate wastes containing 

 nitrogen through the skin and the kidneys. 



(7) Protoplasm can reproduce, that is, form other matter like itself. 

 New plants are constantly appearing to take the places of those 

 that die. The supply of living things upon the earth is not de- 

 creasing; reproduction is constantly taking place. In a general 

 way it is possible to say that plants and animals reproduce hi a 

 very similar manner. We shall study this more in detail later. 



To sum up, we find that living protoplasm has the properties 

 of sensibility, motion, growth, and reproduction alike in its sim- 

 plest state as a one-celled plant cr animal and as it enters into 

 the composition of a highly complex organism such as a tree, a 

 dog, or a man. 



BOOKS FOB REFERENCE 

 ELEMENTARY 



Sharpe, A Laboratory Manual. American Book Company. 



Atkinson, First Studies of Plant Life. Chap. XI. Ginn and Company. 



Snyder, The Chemistry of Plant and Animal Life. The Macmillan Company. 



ADVANCED 



Coulter, Barnes, and Cowles, A Textbook of Botany, Part II. American Book Com- 

 pany. 



Goodale, Physiological Botany. American Book Company. 

 Green, Vegetable Physiology. J. and A. Churchill. 



Parker, An Elementary Course in Practical Biology. The Macmillan Company. 

 Sedgwick and Wilson, General Biology. Henry Holt and Company. 

 Verworn, General Physiology. The Macmillan Company. 

 Wilson, The Cell in Development and Inheritance. The Macmillan Company. 

 HUNT. ES. BIO. 3 



