INTRODUCTION. 3 



animals look alike, act in the same way, move in the same 

 manner, so that in some cases we cannct say which is an 

 animal and which a plant. Also some animals have in 

 their bodies starch and cellulose, while some animals have 

 no substance from which gelatine may be made. 



While, then, living bodies, even the simplest, differ from 

 minerals in manufacturing protoplasm and other substances, 

 such as starch, fat, etc., within their bodies; unlike min- 

 erals, they grow by additions from within. Besides this, 

 they multiply or reproduce, i.e., they set apart a portion of 

 their bodies, as a seed or egg, which may grow up to be an 

 oak or a bird; they have also the power of waste and repair. 



Moreover living things "go." A watch "goes," but 

 such a machine soon stops unless the spring is wound up. 

 When it stops, however, we do not say that the watch dies. 

 When, however, a plant stops going, i.e., when the sap 

 ceases to flow, the leaves wither and the root dries, it dies; 

 when a dog's heart stops beating and the blood ceases to 

 flow, it dies. Minerals do not die. 



So we see that living bodies differ from minerals in four 

 respects: 1. Their bodies contain and are built up of proto- 

 plasm; 2. They grow from within; 3. They reproduce from 

 seeds, germs, or eggs; and 4. All living bodies die. 



FIG. 2. Red-snow, a plant. FIG. 15. A Monad, c, cilia; 

 c, cilia; n. nucleus. (High- n. nucleus; cv, contrac- 

 ly magnified.) tile vesicle. 



The Differences between Plants and Animals. Any 

 child can see that a fern, or lily, or elm-tree are very un- 



