DIVISION OF LABOR 27 



-.adult body with its many tissues and organs. Groups of 

 -cells ceasing to grow and multiply like their parents begin 

 to grow in ways peculiar to themselves, and so come to 

 differ both from the original cells of the morula and from 

 the cells of other groups, and this unlikeness becoming 

 more and more marked, a varied whole is finally built up 

 from one originally alike in all its parts. Peculiar growth 

 of this kind, forming a complex from a simple whole, is 

 called development; and the process itself in this case is 

 known as the differentiation of the tissues, since by it they 

 are, so to speak, separated or specialized from the general 

 mass of mother-cells forming the morula. 



As the differences in the form and structure of the con- 

 stituent cells of the morula become marked, differences in 

 property arise, and it becomes obvious that the whole cell- 

 aggregate is not destined to give rise to a collection of in- 

 dependent living things, but to form a single human being, 

 in whom each part, while maintaining its own life, shall 

 have duties to perform for the good of the whole. In other 

 words, a single compound individual is to be built up by 

 the union and co-operation of a number of simple ones 

 represented by the various cells, each of which thenceforth, 

 while primarily looking after its own interests and having 

 its own peculiar faculties, has at the samAime its activi- 

 ties subordinated to the good of the entireliommunity. 



The Physiological Division of Labor. The fundamen- 

 tal physiological properties, originally exhibited by all the 

 -cells, become ultimately distributed between the different 

 modified cells which form the tissues of the fully developed 

 Body much in the same way as different employments are 

 -distributed in a civilized state; for the difference between 

 the fully developed Human Body and the collection of 

 amoeboid cells from which it started is essentially the same 

 as that between a number of wandering savages and a civi- 

 lized nation. In the former, apart from differences de- 

 pendent on sex, each individual has no one special occu- 

 pation different from that of the rest, but has all his own 

 needs to look after: he must collect his own food and 

 prepare it for eating, make his own clothes if he wears 



