One may always expect in living nature variations and modifications. It is useless to ask why. Nature is silent when interrogated in this way. Ask her how, and you get some results. If we ask, for instance, why the sting of the honey bee is barbed, and those of the hornet and wasp and bumble-bee, and of other wild bees, are smooth like a needle, so that they can sting and sting again, and live to sting another day, while the honey bee stings once at the cost of its life; or why only one species of fish can fly; or why one kind of eel has a powerful electric battery; or why the porcupine has an armor of quills while his brother rodent the woodchuck has only fur and hair, and so on—we make no addition to our knowledge.
But if we ask, for instance, how so timid and defenseless an animal as the rabbit manages to survive and multiply, we extend our knowledge of natural history. The rabbit prospers by reason of its wakefulness—by never closing its eyes—and by its speed; also by making its home where it can command all approaches, and so flee in any direction. Or if we ask how our ruffed grouse survives and prospers in a climate where its cousin the quail perishes, we learn that it eats the buds of certain trees, while the quail is a ground-feeder and is often cut off by a deep fall of snow.
If we ask why the chipmunk hibernates, we get no answer; but if we ask how he does it, we find out that he stores up food in his den, hence must take a lunch between his naps. The woodchuck hibernates, also, but he stores up fuel in the shape of fat in his own body. The porcupine is above ground and active all winter. He survives by gnawing the bark of certain trees, probably the hemlock. We have two species of native mice that look much alike, the white-footed mouse and the jumping, or kangaroo, mouse. The white-foot is active the season through, over and under the snow; the jumper hibernates all winter, and apparently accomplishes the feat by the power he has of barely keeping the spark of life burning. His fires are banked, so to speak; his temperature is very low, and he breathes only at long intervals.
If, then, we ask with Emerson, "why Nature loves the number five," and "why the star form she repeats," we shall be put to it for an answer. We can only say that with living things odd numbers are more likely to prevail, and with non-living, even numbers.
Some seeds have wings and some have not. To ask why, is a blind question, but if we ask how the wingless seeds get sown, we may add to our knowledge.
In our own practical lives, in which experimentation plays such a part, we are often compelled to ask why this result and not that, why this thing behaves this way and that thing that way. We are looking for reasons or causes. The farmer asks why his planting in this field was a failure, while it was a success in the next field, and so on. An analysis of his soil or of his fertilizer and culture will give him the answer.
V. AN INSOLUBLE PROBLEM
That Darwin was a great natural philosopher and a good and wise man admits of no question, but to us, at this distance, it seems strange enough that he should have thought that he had hit upon the key to the origin of species in the slow and insensible changes which he fancied species underwent during the course of the geologic ages, and should thus have used the phrase as the title of his book. Had he called his work the "Variability of Species," or the "Modification of Species," it would not have been such a misnomer. Sudden mutations give us new varieties, but not new species. In fact, of the origin of species we know absolutely nothing, no more than we do about the origin of life itself.
Of the development of species we know some of the factors that play a part, as the influence of environment, the struggle for existence, and the competitions of life. But do we not have to assume an inherent tendency to development, an original impulse as the key to evolution? Accidental conditions and circumstances modify, but do not originate species. The fortuitous plays a part in retarding or hastening a species, and in its extinction, but not in its origin. The record of the rocks reveals to us the relation of species, and their succession in geologic time, but gives no hint of their origin.
Agassiz believed that every species of animal and plant was the result of a direct and separate act of the Creator. But the naturalist sees the creative energy immanent in matter. Does not one have to believe in something like this to account for the world as we see it? And to account for us also?—a universal mind or intelligence