THE DIFFERENTIATION OF TISSUES. 



From the subdivision of labor in advanced communities 

 several important consequences arise. In the first p ! 

 man devoting himself to one kind of work mainly and relying 

 upon others for the supply of his other needs, every sort of 

 work is better done. The man who is constantly making 

 boots becomes more expert than one whose attention is con- 

 stantly distracted by other duties, and he can not only make 

 more boots in a given time, but better ones; and so with the 

 performance of all other kinds of work. In the second place, 

 a necessity arises for a new sort of industry, in order to con- 

 vey the produce of one individual in excess of the needs of 

 limself and his family to those at a distance who may want 

 it, and to convey back in return the excess of their produce 

 which he needs. The carriage of food from the country to 

 cities, and of city produce to country districts, and the occu- 

 pation of shopkeeping, are instances of these new kinds of 

 labor which arise in civilized communities. In addition there 

 is developed a need for arrangements by which the work of 

 .ndividuals shall be regulated in proportion to the wants of 

 ;he whole community, such as is in part effected by the 

 agency of large employers of labor who regulate the activities 

 of a number of individuals for the production of various 

 articles in the different quantities required at different times. 



Exactly similar phenomena result from the subdivision of 

 iabor in the Human Body. By the distribution of employ- 

 ments between its different tissues, each one specially doing 

 one work for the general community and relying on the 

 others for their aid in turn, every necessary work is better 

 performed. And a need arises for a distributive mechanism 

 by which the excess products, if any, of various tissues shall 

 be carried to others which require them, and for a regulative 

 mechanism by which the activities of the various tissues shall 

 be rendered proportionate to the needs of the whole Body at 

 different times and under different circumstances. 



Classification of the Tissues. As we might separate the 

 inhabitants of the United States into groups, such as lawyers, 

 doctors, clergymen, merchants, farmers, and so forth, so we 

 may classify the tissues by selecting the most distinctive 

 properties of each of those entering into the construction of 

 the adult Body and arranging them into physiological groups; 

 those of each group being characterized by some one promi- 

 nent employment. No such classification, however, can be 



