Page:Popular Science Monthly Volume 85.djvu/468

464 forces. To understand them is, they admit freely, beyond their ken. Thereby, even if their own problem were solved, a purely materialistic view would hardly be appreciably advanced.

But to return. Life, like electricity, can not be defined, but, like it, manifests itself in certain ways. Movement, metabolism, growth and reproduction are held to be characteristic properties of life by a large class of physiologists; but the insurgent group, with Wöhler's artificial production of urea—wherein he overthrew the idea that organic substances possess a "vital" force—as its foundation stone, is bent upon showing us that there is no such barrier between the animate and the inanimate. Is it movement that you are considering? Have we not that in organic mixtures, in oil drops, in globules of mercury? And are these not all explicable by changes in surface tension? Is it metabolism—the taking in of food and the giving out of waste products? If so, what of osmotic conditions, where solutions are separated by semi-permeable membranes and where there is an interchange of substance? Is it growth and reproduction? If so, consider the growth and multiplication of crystals.

It is this argument by analogy that has led the ultra-scientific school to its present theory with regard to the origin of life. Rightly brushing aside the meteoric theories of Kelvin, Helmholtz and Arrhenius as irrelevant in so far as origin goes—for in their attempt to explain the first sign of life on this planet they presuppose the existence of the germ elsewhere—Schäfer boldly upholds the hypothesis that life originated as a result of the gradual evolution of inanimate material. In process of time the simple substance became more and more complex and ultimately emerged as the living germ—the nitrogenous colloid.

But Schäfer goes a step further. Why are we to suppose that this happened but once, as all theories with regard to origin have thus far assumed? Why are we to suppose that at one time in the dim past a series of fortunate accidents made life possible? Is it not more logical to assume that these evolutionary processes are going on today and will continue to do so?

Though even Huxley was of the opinion that at one time there was "an evolution of living protoplasm from not living matter," the idea that we should not relegate the process to some remote period in the past is a comparatively new one, and has not by any means received the approval of many otherwise loyal chemico-physiologists. These argue with no small show of reason, that continuous life production would imply similar terrestrial conditions throughout the ages; and this we know not to be the case.