Page:American Journal of Sociology Volume 8.djvu/799

 INTRODUCTION TO SOCIOLOGY. III.'

PART III. GENERAL STRUCTURE OF SOCIETIES.

CHAPTER IV. THE SOCIAL LIMITS. SECTION V. BIOLOGICAL LIMITS. Continued.

HOWEVER, protoplasm itself has a structure. There is an organism having the structure of an amoeba, without any mem- brane other than its geometrical limit, and without a nucleus, but it has the essential elements of a nucleus distributed through- out the protoplasm. After the central mass is separated from the periphery with which it is blended, the organism becomes a cell. Every organism is a cell or a combination of cells. The ensemble of the forms of the whole organism is then the product or general total of all the aggregated cells. Thus the forms of elementary organisms are : ( I ) forms without a membrane and without a nucleus ; ( 2 ) forms with a nucleus and without a membrane ; ( 3 ) forms with a nucleus and a membrane. With each step in the progress of organization, the equilibration to the environment becomes more perfect ; that is to say, the organism maintains itself by adaptations to more numerous and more special conditions. But, as among plants, this structure, differ- entiated into a nucleus and a membrane, though it suffices for the unfolding of its life, and for resistance, especially in a passive way, to the environment, is not adequate for more complex, pre- cise, and especially active adaptations. This unicellular state forms the basis of the multicellular ; that is to say, for an asso- ciation of simple homogeneous cells. In the multicellular organisms there is a differentiation into an external and an inter- nal layer. In plants this external and protecting layer is the epidermis, the inner and assimilating layer being the parenchyma ; in the animals, the external sensitive and protecting surface is the ectoderm, and the interior and assimilating membrane, or endoderm, forms the boundary of the digestive cavity, which does

1 Translated by Eben Mumford.

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