30 THE HUMAN BODY. 



ail its parts. Peculiar growth of this kind, forming a com 

 plex from a simple whole, is called development; and the pro 

 cess itself in this case is known as the differentiation of tli 

 tissues, since by it they are, so to speak, separated or special 

 izcd from the general mass of mother-cells forming th 

 morula. 



As the differences in the form and structure of the con 

 ells of the morula become marked, differences ii 

 property arise, and it becomes obvious that the whole cell 

 gate is not destined to give rise to a collection of hide 

 pendent living things, but to form a single human being, ii 

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

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

 a single compound individual is to be built up by the unio] 

 and co-operation of a number of simple ones represented b 

 the various cells, each of which thenceforth, while primaril 

 looking after its own interests and having its own peculia 

 faculties, has at the same time its activities subordinated t 

 the good of the entire community. 



The Physiological Division of Labor. The fundaments 

 physiological properties, originally exhibited by all the cells 

 become ultimately distributed between the different modifie 

 cells which form the tissues of the fully developed Bod 

 much in the same way as different employments are dis 

 tributed in a civilized state; for the difference between th 

 full} developed Human Body and the collection of amosboi 

 cells from which it started is essentially the same as tha 

 between a number of wandering savages arid a civilized natioi 

 In the former, apart from differences dependent on sex, eac 

 individual has no one special occupation different from tha 

 of the rest, but has all his own needs to look after: he mug 

 collect his own food and prepare it for eating, make his ow 

 clothes, if he wear any, provide his own shelter, and defen 

 himself from wild beasts or his fellow men. In the civilize 

 country, on the other hand, we find agriculturists to rais 

 food and cooks to prepare it, tailors to make clothes, an 

 policemen and soldiers to provide protection. And just 

 we find that when distribution of employments in it is moi 

 minute a nation is more advanced in civilization, so is a 

 annual higher or lower in the scale according to the degre 

 in which it exhibits a division of physiological duties betwee 

 its different tissues. 



