The Message of Science. 35 



another to securing food, and still another to digestion 

 and assimilation of the food. 



Soon, indeed, one cell, or group of cells, in the union, 

 took upon itself the office of spying out food, or sighting 

 danger and notifying the motive group to move forward 

 swiftly, or to beat a hasty retreat. This spy cell, or group 

 of cells, soon assumed the leadership. In time, complete 

 differentiation of labor-function was effected. The loco- 

 motive or muscle group not only performed no other kind 

 of labor, but became unable to perform other. Its internal 

 organization conformed to this want of the union. So of 

 the group which seized, or digested food, and preemi- 

 nently so of the spy cell group which erelong devoted 

 itself exclusively to discernment, intelligent decisions and 

 a general directorate and protectorate of the other groups. 



This apparent development of metazoons from proto- 

 zoons, of so great significance in the terrestrial scheme of 

 life, was set forth by this author some years since a little 

 more in detail. 



"Very soon after creatures composed of many cells 

 (metazoons) were developed from groups of unicellular 

 life, the necessities of locomotion in the struggle for food 

 led to the differentiation of certain tracts of cells as bone 

 and muscle, and finally to the development of the entire 

 apparatus for mechanical movements. 



" Simultaneously, too, another peculiar species of dif- 

 ferentiation began to be necessary, namely, a special tis- 



