Page:Popular Science Monthly Volume 79.djvu/133

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THE INTERPRETATION OF NATURE

nature that has been poured upon this generation, the whole thing has come about from a certain unappeased popular demand. There is a widespread and rapidly growing curiosity about and interest in animate beings. Such curiosity and interest lead inevitably to efforts for increased knowledge. The authoritative biology of the day has failed and is failing to meet this demand.

Let any teacher of botany or zoology in school or college, whose experience reaches back twenty years, consider the men and women of today who were once his pupils. Let him ask himself to what extent his efforts succeeded in making the plants and animals by which these men and women have since been constantly surrounded, vital, potent, perennial elements in the effectiveness of their lives. Testing your work thus, does the voice of conscience say well done? It surely does not for me, and I have no reason to suppose the instruction I gave during some fifteen years to general classes in the University of California was particularly worse than that given by most teachers. I made use of the regulation paraphernalia in the regulation way. There were the innumerable wall-charts carefully drawn and colored, with the proper conventions for ectoderm, mesoderm and entoderm, and for the various cell-parts during indirect cell-division, fertilization, and so forth. A fairly complete set of preparations to illustrate the lectures was at hand, some in bottles, some dry. The fundamental nature of living substance, "according to the latest and best authorities," and the fundamental difference between plants and animals, were early and concisely set forth. Near the beginning of the course the doctrine of evolution was made clear and impressive, and strong enough to sustain the weight of every fact that should later be brought forward.

The vast importance from the evolutionary standpoint of a few fundamental types, amœba, volvox, the calcareous sponges, the primitive annelid, Amphioxus, the shark, was duly insisted upon. The gastrula, the cœlome, the nephridia, the somites of the vertebrate head, and the rest of the thirty-nine articles of evolutionary faith were set forth. The "factors" of evolution were treated with generosity. Natural selection was of course given first place, but later mutation became its close second. Not only colored figures, but an actual specimen, naturally environed in a glass case, of Kallima, that wonderful leaf-butterfly which has been the cornerstone of a whole philosophy, was provided to illustrate protective resemblance; and various other instances of adaptation were shown. When the topic of animal psychology was reached, it was pointed out how easily and completely the tropism theory disposes of the vagary of earlier notions about the intelligence of lowly creatures, and the interesting point was made that in a simple caterpillar "reacting" up a stick we probably have in our hands the key to the whole mystery of mind in the living world.