Page:Popular Science Monthly Volume 79.djvu/267

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SYSTEMATIC ZOOLOGY

clear our central purpose and formulate some of the principles that guide us in our work. In attempting to do this, I am obviously speaking only for myself. I could not, even if I would, express another worker's motives or principles. The excuse for publishing my own is two-fold; the thought that they may be in some way suggestive to other systematists, and the larger hope that they may serve to increase the mutual sympathy between all classes of zoologists.

There seem to be at least three current opinions as to systematic zoology. One is that it is engaged in the vast undertaking of cataloguing the animal kingdom. Every species of animal must be listed and hence must have a name, or, at least, a number. That the names may be attached to the right animals, descriptions and figures must be published. As there are still an unknown number of unnamed species, the describing of new species is the most important part of systematic work. The remainder consists of arranging in some sort of comprehensible system the thousands of names already in use. This type of systematic work is well shown in Linné's "Systema Naturæ," the purpose of which is, frankly, to give a complete catalogue of all natural objects. The confidence that such a catalogue would be immensely useful for many purposes was a sufficient incentive to undertake the labor involved.

A second opinion of systematic zoology, which has found expression several times since the opening of the twentieth century, is at the other extreme from the preceding. This very modern view is that systematic zoology covers the whole field—morphology, physiology, embryology, histology, paleozoology, even cytology are but assistants in systematic work. As taxonomic characters occur obviously on the exterior, so they occur no less really, though obscurely, in the internal structure, in the performance of functions, in the tissues, in the development, even in the mitotic figures in the cells. As comparative study of recent animals is essential to a proper understanding of character values, so the careful study of fossils and the revelations of the geological record are supremely important for systematic work. According to this view, the systematist is not the assistant erecting the scaffolding with the aid of which the real building is to be done by the other specialists, but he is himself the master-builder and the others are the carriers of material with which he may build.

The third opinion of systematic work, held in some degree by many zoologists, though often more or less unconsciously and seldom openly avowed, is that it forms an elementary sort of study which has a certain educational value in training the eye and the judgment of those who are to become zoologists. It bears much the same relation to zoology proper that arithmetic does to what we call higher mathematics, and the really able man will not delay in it, after he has secured the training