66 THE LIVING WORLD. 



there shown, multiplication simply consists of the 

 division of the original cell into parts, each of which 

 is like the other, and each of which is henceforth 

 independent of the others. Now such multiplica- 

 tion is universal in the unicellular organisms ; such 

 a multiplication is nearly universal among the cells 



FIG. 4. Amoeba in the act of dividing. The nucleus, N, has already separated 

 in two parts. 



of the bodies of higher animals ; such a multiplication 

 is the universal method by which the single-celled 

 ovum begins to grow and develop into the many- 

 celled adult. From all of this there can be no room 

 for doubt that such a method of multiplication was 

 possessed by the earliest unicellular animals, which 

 we must assume lived at the very beginning of the 

 history of life in early ages. 



* 



The history of the living world has been like that 

 of a branching tree, a main trunk dividing into 

 branches, and these in turn subdividing until they 



