64 THE ASCENT OF THE BODY. 



great that count is lost, and the activity becomes so 

 vigorous in every direction that one ceases to notice 

 individual cells at all. The tenement in fact consists 

 now of innumerable groups of cells congregated to- 

 gether, suites of apartments as it vrere, which have 

 quickly arranged themselves in symmetrical, definite, 

 and withal different forms. Were these forms not 

 different as well as definite we should hardly call it an 

 evolution, nor should we characterize the resulting 

 aggregation as a higher organism. A hundred cot- 

 tages placed in a row would never form a castle. 

 What makes the castle superior to the hundred cot- 

 tages is not the number of its rooms, for they are pos- 

 sibly fewer ; nor their difference in shape, for that is 

 immaterial. It lies in the number and nature and 

 variety of useful purposes to which the rooms are pat, 

 the perfection with which each is adapted to its end, 

 and the harmonious co-operation among them with 

 reference to some common work. This also is the dis- 

 tinction between a higher animal and a humble organ- 

 ism such as the centipede or the worm. These 

 creatures are a monotony of similar rings, like a string 

 of beads. Each bead is the counterpart of the other ; 

 and with such an organization any high or varied life 

 becomes an impossibility. The fact that any growing 

 embryo is passing through a real development is de- 

 cided by the new complexity of structure, by the more 

 perfect division of labor, and of better kinds of labor, 

 and by the increase in range and efficiency of the cor- 

 related functions discharged by the whole. In the 

 development of the human embryo the differentiating 

 and integrating forces are steadily acting and co-oper- 

 ating from the first, so that the result is not a mere 



