4 MARINE BIOLOGICAL LABORATORY. 



its chief distinction from a purely gregarious aggre- 

 gate. 



If the members of such a community, in adaptation to 

 the conditions it imposes, should become so far differ- 

 entiated as to lose the power of providing for more 

 than one or two of the ten necessities of existence, 

 the social unity would become as inviolable as the 

 physiological unity of the higher organisms. Break 

 it, and every member would soon perish, just as certainly 

 as every cell would die if the body were irreparably 

 injured. The social organism might endure the loss 

 of a Ijmited number of its members, as the animal 

 organism survives the death of individual cells and 

 even the loss of certain organs. These losses may be 

 repaired, in the one case by substitution, in the other 

 by regeneration. 



If reparation fails, all the remaining parts suffer in 

 proportion to their dependence on the parts lost. In 

 either case, the more complete the division of labor, 

 broadly speaking, the more perfect becomes the unity 

 of parts, the more complete the coincidence of the indi- 

 vidual with the general welfare. 



The parallel is more complete than our assumed case 

 is suited to illustrate. We have considered only the 

 two extremes of a series, and have not allowed for any 

 connection through intermediate stages of development. 

 But division of labor is not an artificial affair arbitrarily 

 fashioned to our convenience ; it is not a thing of human 

 device, for it antedates both the written and the un- 

 written history of our race. In the organic world, its 

 development has been as slow and as long as the rise 

 of the beings now inhabiting the earth ; in the human 



