INTRODUCTION TO SOCIOLOGY 833
living bodies, /. e., between their contour and their composition. I call attention to this law ; it is important because it gives us a glimpse of the scientific theory of social frontiers; that is to say, of the external and differentiated aspects of society, as we shall develop below. Between the biological and the sociological theories there is little difference, just as there is between the biological and the physico-mechanical theories.
Let us suppose, with M. Le Dantee, that a certain amount of oil is poured into a salt solution of the same density. The oil will take the form of a sphere and will remain in equilibrium. If the solution is perfectly quiet, a sphere of large dimensions can be formed. If on the other hand, the liquid is violently agitated, the oil will break up into a large number of small spheres, as small as the agitation is great; the degree of agita- tion determines the dimensions possible for the particles of the oil.
It is the same in organized matter. On a level with the line of separation of living protoplasm from its surroundings a series of changes continually exists, which develops in that separating zone an intense agitation. The limitations of normal dimensions of the masses of protoplasm is then a very natural phenomenon. Limitation necessarily results, for there is no more absolute rest in protoplasm than in the liquid or the drop of oil. Not only is the greatest dimension of the protoplasmic masses limited, but the form of these masses results from the mechanical conditions about them, caused by molar movement, by changes. But M. Le Dantee concludes:
This movement is the result, partly of the nature of the substance of the protoplasm, a nature peculiar to the chemical composition of protoplasm, and partly of the chemical reactions within the protoplasm which keep up the molar movement, and which depend upon the chemical composition of the protoplasm as well as upon the nature of the chemical elements borrowed from milieu.
The form of living substances is the result of their state of equilibrium. This is why, so long as an animal lives, its sub- stance, being of spherical units, always tends to maintain, while growing, the form which is the specific form of its own
