Page:George Archdall Reid 1896 The present evolution of man.djvu/72

60 somatic cells, by billions, and during every moment of time some of the somatic cells are perishing and others are proliferating. Therefore to discover the number of gemmules sent off by the somatic cells of an organism to its germ cells, we must multiply the millions of the germ cells by the billions of the somatic cells, and then multiply the product by the moments of time, multiplied by the number of the separate acts ol cell-proliferation and death occurring during each moment of time. This consideration renders the theory wholly incredible, and it is rendered almost unthinkable if we take into consideration also that each germ cell is a mere speck as compared to the rest of the body; that the blood, a fluid mass of considerable volume, must accurately bring from every part of the body to each of these specks its appropriate billions of gemmules, and that, when arrived, each gemmule must take up its proper position in the germ cell so as to cause it, when fertilized, to develop into an organism similar to that of which it (the germ cell) forms an infinitesimal part. It is hard to believe that such a theory can ever have been seriously entertained by biologists of note, and that notwithstanding the fact that it is wholly inapplicable, as is the preceding theory, to plants, the nutrient fluids of which flow generally in one direction and do not circulate in the sense that the nutrient fluids of animals circulate.

The third theory is one formulated by Mr. Herbert Spencer. I give his own words as far as space permits.

"As we shall have frequent occasion hereafter to refer to units, which possess the property of arranging themselves into the special structures of the organisms to which they belong, it will be well here to ask what these units are, and by what name they may be most fitly called?