Page:Popular Science Monthly Volume 16.djvu/669

 sociology and the branches of biology that are occupied with the constitution and functions of organisms.

We now reach the ultimate elements of living bodies, the material which has served to make the most simple beings, and we ask, What is its origin? Here we are in the presence of unity; there is no longer any question of association. Most living cells are composed of four parts—a membranous envelope, a contained fluid in which is a special globule, and the nucleus, containing the nucleolus. Of these four parts only one, the contained semi-fluid, perfectly limpid or finely granular, the protoplasm, is indispensable. It is in this strange substance that life, which needs no other apparatus to manifest itself, resides. Those remarkable beings, the Monera, are formed of it alone. They are simple, homogeneous clots of a limpid jelly like the white of egg. This jelly has the power of movement, captures animals, digests and assimilates them, grows, and, when it has attained a certain size, divides into two or several masses, that begin anew the life of their mother, and divide like her when they have reached a certain size.

This faculty of division is an important property of protoplasm, because it governs all organic evolution. A protoplasmic mass can not exceed a determinate size. When it reaches this size, a partition forms, and, as its mass is perfectly homogeneous, as it is constantly traversed by currents that completely mingle its substance, all the resulting fragments possess the acquired or hereditary properties of the protoplasmic mass from which they came. This explains all the phenomena of heredity, by means of which each being transmits to its progeny, even in the case of sexual generation, all its specific and part of its personal characters.

From this incapacity of protoplasmic masses to exceed a certain length, it follows that all beings that are larger must be formed of several distinct masses of protoplasm—in a word, are colonies. So the generality of the law of association appears as a consequence of one of the fundamental properties of protoplasm. It constantly decomposes itself into distinct masses. These separate masses are modified, each in a particular fashion, under the influence of external agents. Hence the wonderful variety of nature is an immediate consequence of the law of association, of the. necessity imposed upon protoplasm to separate into small distinct individualities.

What, then, can be the nature of protoplasm? Struck by its homogeneity, the identity of the elements that compose it with those that form albuminoid substances, it has been taken for a mere chemical compound, and it has been boldly asked if it is not possible to produce it artificially; if man has not power to relight the torch of Prometheus and create life at will. This question, I believe, has been asked in consequence of a strange confusion of words. If it is true that the substances that form living matter are the same as those that enter