8 THF: AMERICAN BOTANIST 



and old age. In the end they die and the elements of which 

 they were formed become disassociated and may again form 

 part of other organisms, hut the elements themselves have 

 neither a youth, maturity, nor old age that can be measured 

 by our common time standards. But though the individuals 

 may die. the group to which they belong does not disappear 

 because it is constantly being renewed by processes of repro- 

 duction which all possess w^iereby, on coming to maturity, 

 they give rise to smaller and younger organisms like them- 

 selves. Lifeless matter cannot reproduce or increase in this 

 way; in fact, no new forms of living matter originate of them- 

 selves. All life from pre-existent life is the law. 



To carry on the business of living, or in any other activity, 

 a certain amount of energy is needed. This energy plants se- 

 cure from the sunlight, by means of the green coloring matter 

 known as chlorophyll. This color is able to change some of 

 the light energy falling on it to electrical energy and by means 

 of this, plants combine hydrogen, oxygen and carbon into 

 foods, which, like storage batteries, hold the energy until it is 

 desirable to release it. Oxidizing the foods releases the en- 

 ergy. Th's latter process is called respiration and is practi- 

 cally efpiivalent to breathing, as commonly understood. The 

 animals laci< this green coloring matter and cannot make food 

 for themselves. They therefore rob the plants for their own 

 uses. Kven man, hiiriself. finds it necessary to do this. 



The simplest plants consist of single cells but the size of 

 such organisms in no way limits the functions that distinguish 

 living things from non-living. Although most of the plants 

 with w^hich we are familiar are made up of vast aggregations 

 of cells, there are manv one-celled organisms on the earth. 

 Practicallv all of the germs that cause disease in man, the other 

 animals and the plants are one-celled, while it is well known 



