Z INTRODUCTORY REMARKS. 



animals. They suck up the water contained in the ground by 

 means of their roots. They cannot move from place to place 

 like animals, but always remain fixed where the seed fell, and 

 took root; and, lastly, if we cut off a branch from a tree, it does 

 not seem to experience any pain it does not feel. 



Minerals are always easy to recognize. They have no life 

 like plants and animals, and they do not reproduce their species 

 like these, by young ones, eggs, or seeds. 



The mineral, vegetable, and animal kingdoms supply man 

 with everything which he requires for his food ; to build houses, 

 to clothe and warm himself, or to construct tools. 



The study of these three kingdoms forms what is called, collec- 

 tively, the Natural Sciences, and as these concern all the beings 

 and objects which surround us, and without which we could not 

 live, it is clear that we ought to know them, and that the 

 study of the Natural Sciences is very useful indeed. 



To enable us to recognize objects among the innumerable 

 number of animals, plants, and minerals which the earth contains, 

 it is necessary to establish an arrangement which allows of our 

 distinguishing every object. This arrangement is what is called a 

 classification. To attain this end, it has first been attempted to 

 group together all those animals which have certain points of 

 resemblance in common ; all those, for instance, which suckle 

 their young with teats have been called mammals ; all those 

 with feathers are called birds. The same with reptiles, fishes, 

 insects, and molluscs. All those large groups of animals which 

 have certain very important characters in common, have been 

 called classes. We speak of the class of birds, the class 

 of fishes, etc.; but each class comprises within itself so large a 

 number of animals that these great divisions would not be 

 sufficient. The class of mammals, for instance, alone includes 

 very different animals. The bat which flies like a bird, the 

 whale which lives in the water like a fish, and the horse which 

 runs on the ground, are all three mammals ; they all three 

 forth young which they suckle, and yet these three 



