CHAPTER I. 

 THE AMCEBA AND OTHER ROOT-ANIMALCULES. 



THIS book begins with the lower, simpler, one-celled ani- 

 mals and ends with the more complex, i.e., birds and beasts, 

 since this is the most natural method. The lower forms of 

 animal life, such as worms, shell-fish and insects, appeared 

 in the earth's history before the back-boned creatures. It 

 is therefore better to lead the student from the simpler and 

 earlier to the more complex and later animal forms, just as 

 in studying history we begin with that of uncivilized or 

 barbarous peoples, and study their progress upward to civi- 

 lization. To begin the study of zoology by first taking up 

 the beasts and birds is like reading history backwards. 



We will begin our lessons, then, with the simplest being 

 we can readily find, and that is the Amoeba (Fig. 7). It 

 is to be sought for in standing pools, where it lives on the 

 leaves or stems of submerged plants, or in the mud or ooze 

 at the bottom. Taking up a drop of water from the bottom 

 of such a pond and placing it under high powers of the 

 microscope, we may, after close examination, detect a 

 very small, moving mass of jelly-like substance or pro- 

 toplasm. As it glides over the glass the sides of its body 

 bulge out, or it suddenly throws out lobes or projections 

 from various parts of its body as if it were falling apart; 

 then it retracts these transparent root-like processes, which 

 are called pseudopodia, or false feet, and becomes smooth 

 and rounded, like a drop of thick syrup. Throughout the 

 body-mass are granules which have a rude sort of circula- 

 tion. There is also in or near the middle a clear round 

 body called the nucleus. In all respects the Amoeba is a 

 cell, i.e., a bit of protoplasm with a nucleus in the middle. 



