THE LIFE CYCLE 49 
death. The new Amede are from their beginning like the 
full-grown Ameba, except as regards size. And the old 
Ameba does not die, because its whole body continues to 
live, although in two parts—the two new Amebe. The life 
cycle of the simplest animals includes birth (usually by 
simple fission of the body of the parent), growth, and some, 
but usually very little, development, and finally the repro- 
duction of new individuals, not by the formation of eggs, 
but by direct division of the body. 
48. The egg.—In our study of the multiplication of ani- 
mals (Chapter III) we learned that it is the almost univer- 
Fie. 38.—Eggs of different animals showing variety in external appearance. a, egg 
of bird ; 5, eggs of toad; c, egg of fish; @, egg of butterfly ; e, eggs of katydid 
on leaf ; f,egg-case of skate. 
‘gal rule among many-celled animals that each individual 
begins life as a single cell, which has been produced by the 
