THE ELEMENTS OF ORGANIC EVOLUTION. 



93 



It never becomes selfish except in its perversion. Its 

 perversion is its destruction. And from the simple altru- 

 istic beginnings of the conjugation of cells in those 

 simple organisms arise with evolution all the complex 

 possibilities of love, conjugal, filial, and parental. 



In another way the altruistic tendencies are shown 

 in the aggregation of cells. Among animals of one cell 

 the ordinary processes of division give rise to a new 

 organism for each division. But if the new cells formed 

 by such subdivision still remain attached to each other, 

 a complex organism is built up. It is thus that the 

 single germ cell in the higher animals grows into the 

 embryo, and the embryo through the stages of infancy 

 and youth into the adult organism. 



The co-operation of the members of the colony of 

 cells of which the compound animal is composed makes 

 possible all the various forms of organic differentiation. 

 A single cell is a unit, complete in itself and inde- 

 pendent. All the functions possible to it are united in 

 a single structure. With a complex organism the dif- 

 ferent cells are gathered into groups to form tissues. 

 Out of these tissues different organs are built up, and 

 each different organ performs a distinct function. In 

 the compound structure of man a multitude of cells are 

 joined to perform the work of assimilation, and a host 

 of others purify the blood ; to another multitude is as- 

 signed the task of locomotion. Still others, of finer tex- 

 ture, receive impressions of external things and trans- 

 mit these impressions into the phenomena of motion. 

 Specialization, differentiation, organization, and the ex- 

 quisite functions of nerve tissue, are all resultants of the 

 altruistic co-operation of cells. As individual men under 

 altruistic impulses unite together to form societies and 

 states, so are individual cells gathered together to form 

 the human body. The conjugation of cells is a method 



