136 THE STORY OF THE LIVING MACHINE. 



accurately performed, and hence raised somewhat 

 the totality of life powers. This parcelling out of 

 the different duties of life to groups of cells con- 

 tinued age after age, each step being a little ad- 

 vance over the last, until the result has been the 

 living machine as we know it in its highest form, 

 with its numerous organs, all interrelated in such 

 a way as to form a harmoniously acting whole. 



But a second principle in this growth of the 

 machine was needed to produce the variety which 

 is found in nature. As the different cells in the 

 multicellul'ar mass became associated into groups 

 for different duties, the method of such division of 

 labor was not alike in all machines. A city in 

 China and one in America are alike made up of 

 individuals, and the fundamental needs of the 

 Chinaman and the American are alike. But dif- 

 ferences in industrial and political conditions 

 have produced different combinations and asso- 

 ciations, so that Pekin is wonderfully unlike New 

 York. So in these early developing machines, 

 quite a variety of method of organization was 

 adopted by the different groups. Now as soon 

 as any special type of organization was adopted 

 by any animal or plant, the principle of heredity 

 transmitted the same kind of organization to its 

 descendants, and there thus arose lines of descent 

 differing from each other, each line having its 

 own method of organization. As we follow the 

 history of each line the same thing is repeated. 

 We find that the representatives of each line 

 again separate into groups, each of which has ac- 

 quired some new type of organization, and there 

 has thus been a constant divergence of these lines 

 of descent in an indefinite number of directions. 

 The members of the different lines of descent all 



