144 Sioux City Academy of Science and Letters. 



the subject. The lowest plants and animals are so close- 

 ly related, that it is hard to draw any fast line separating 

 them from each other. But there is this fundamental 

 difference between the tw^o forms of life, which has, how- 

 ever, a very few exceptions, that will be spoken of later. 

 The plant alone has the power of converting lifeless in- 

 organic matter into living organic cells, while the animal 

 cannot do this. So that the manner of obtaining nutri- 

 ment must make the difference between the two forms of 

 life. All organic life must be supported fundamentally 

 by inorganic material drawn from the earth and atmos- 

 phere. The plant alone is able to do this by the aid of 

 what we call chlorophyll, which gives the green color to 

 vegetation. This chlorophyll absorbs certain parts of the 

 sun's rays, which set up a chemical action and separating 

 carbon from the oxygen in the carbonic acid gas in the 

 air, and also hydrogen from the oxygen of the water, thus 

 form hydrocarbons, w^hich are a source of energy. Now 

 if the animal is unable to do this, it must depend upon 

 the plant for its energy, and so we must believe that 

 plant life existed before animal life. This belief is sub- 

 stantiated by the paleontological story of the oldest 

 rocks in which distinct fossils have been found, so they 

 are mostly plant remains. 



Some naturalists have contended that the earliest 

 protoplasm did not contain chlorophyll. They contend 

 that chlorophyll is a modification of protoplasmic cells 

 and, therefore, a subsequent acquirement slowly gained. 

 It w^ould seem, however, that plant life must have been 

 first, because life is a product of power operating under 

 its separating action of energy upon matter, and so an 

 energy storing organism must have come first. T have 

 already said that it is difficult to draw a. line clearly 

 separating the plant from the animal. There are a few 

 forms of plant life that do not possess chlorophyll, and, 

 therefore, can exist without light. There are also a few 

 of the lowest of the animal forms that do contain chloro- 

 phyll and exist in certain conditions. These very few 

 exceptions, however, do not affect the rule which we may 

 state as, life is due to energy received from the rays of 

 the sun, and this energy is powerless without the chloro- 



