The single cell has the power of choice, for it refuses to eat what is unwholesome and extends itself mightily to reach that which is nourishing.
[The Cell and Organic Evolution]
Moebius and Gates are convinced that the single cell possesses memory, for having once encountered anything dangerous, it knows enough to avoid it when presented under similar circumstances. And having once found food in a certain place, it will afterwards make a business of looking for it in the same place.
And, finally, Verwörn and Binet have found in a single living cell manifestations of the emotions of surprise and fear and the rudiments of an ability to adapt means to an end.
Let us now consider pluricellular organisms and consider them particularly from the standpoint of organic evolution. The pluricellular organism is nothing more nor less than a later development, a confederated association of unicellular organisms. Mark the development of such an association.
[Evolutionary Differentiations]
Originally each separate cell performed all the functions of a separate life. The bonds that united it to its fellows were of the most transient character. Gradually the necessities of environment led to a more and more permanent grouping, until at last the bonds of union became indissoluble.
Meanwhile, the great laws of "adaptation" and "heredity," the basic principles of evolution, have been steadily at work, and slowly there has come about a differentiation of cell function, an apportionment among the different cells of the different kinds of labor.
As the result of such differentiation, the pluricellular organism, as it comes ultimately to be evolved, is composed of many different kinds of cells. Each has its special function. Each has its field of labor. Each lives its own individual life. Each reproduces its own kind. Yet all are bound together as elements of the same "cell society" or organized "cell state."