Page:Popular Science Monthly Volume 24.djvu/406

392 back to the genesis worked out by Mr. Herbert Spencer in the part of his "Principles of Psychology" entitled "Physical Synthesis."

For let us for a moment try to imagine a nervous system being produced, or increased in value, by natural selection of spontaneous variations alone, without the aid of functional variations at all. It is easy to see that an animal or a plant may vary indefinitely here or there in color, or in hardness of skin, or in woodiness of tissues, and so forth; and it is easy to see that among these truly "accidental" variations some may be better adapted to their particular environment than others. But can we imagine, say, an eye to be produced by a series of such individual accidents? I do not say a human eye, but a simple pigment cell, with a nerve given off from it to a ganglion as in the case of the Amphioxus? And if we can imagine this (which I can not), can we imagine a child being born into the world, gifted, I do not say with innumerable faculties never possessed by his ancestors, but with a single nerve-cell or nerve-fiber more than they possessed? Just let us look at what a palpable absurdity this notion implies.

Here is William Jones's head, containing an average human brain, developed on the same pattern as his father's brain (or as his father's in part and his mother's in part): and here in a particular spot in a particular convolution of it, by a combination of mere physical circumstances, has arisen a totally new and hitherto non-existent nerve-cell. Clearly, this is an acquisition to the race, by way of spontaneous variation. But what is the functional use of this new nerve-cell? What physical circumstance decides whether it is to answer to a new movement in the left little finger, or to a single creative element in the composition of a future fugue? Let us grant a little more: let us suppose the surrounding cells are all concerned in the appreciation of color, or in the manipulation of numbers. Will the new cell in the first case answer to a new and hitherto undiscovered color or to a further aesthetic pleasure in an existent color, or to a higher synthesis into which colors enter as elements; or what in the second case will be its mathematical value? Again, what good will it be without a whole network of connecting fibers which will link it to percipient structures in the eye on the one hand, and to all the various higher layers in the stratified hierarchy of color-thought elements or number-dealing elements on the other hand? Granted that one man in a hundred was born with one such new cell in his brain, and (setting aside the question how the cell comes to have any function at all) what are the