Page:Popular Science Monthly Volume 30.djvu/871

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This volume includes twenty-one essays which represent the reflections that suggested themselves to the author while he was engaged in special zoölogical and paleontological studies. These studies related particularly to the vertebrates, but they impressed the conviction that the conclusions derived from them were also applicable to invertebrate animals and plants. The law of natural selection of Wallace and Darwin is regarded by Professor Cope as only restrictive, directive, conservative, or destructive of something already created. It includes no active or progressive principle, but "must first wait for the development of variation, and then, after securing the survival of the best, wait again for the best to project its own variations for selection. In the question as to whether the latter are any better or worse than the characters of the parent, natural selection in no wise concerns itself." The expression, "survival of the fittest," with which Spencer epitomized this law, is pronounced "neat," and "no doubt covers the case, but it leaves the origin of the fittest entirely untouched." It is proposed, then, to seek for the originative laws by which the materials whence the selection is made are furnished—"in other words, for the causes of the origin of the fittest." The laws which have regulated the successive creations, as the author attempts to define them in his essay on the "Origin of Genera," appear to him to have been of two kinds: the first, that which has impelled matter to produce numberless ultimate types from common origins; and, second, that which expresses the mode or manner in which this first law has executed its course, from its beginning to its determined end. The origin of genera is assumed to be a more distinct subject from the origin of species than has been supposed. A descent with modification involves continuous series of organic types through one or many geologic ages, and the coexistence of such parts of such various series at one time as the law of mutual adaptation may permit. These series, as now found, are of two kinds—the uninterrupted line of specific, and the same uninterrupted line of generic characters. These are independent of each other, and have, as it appears to the author, been developed pari passu, so that he conceives it "highly probable that the same specific form has existed through a succession of genera, and perhaps in different epochs of geologic time"; or, as it is otherwise expressed, species may be transferred from one genus to another without losing their specific characters, and genera from one order to another without losing their generic characters." These explanations may help to make more clear the bearing of what may be regarded as the leading doctrines of Professor Cope's theory, which are, in brief, that the development of new characters has been accomplished by an acceleration or retardation in the growth of the parts changed; that an exact parallelism exists between the adult of one individual or set of individuals, and a transitional stage of one or more other individuals—to be distinguished from the inexact parallelism of Von Baer, a law which expresses the origin of genera and higher groups because they can only be distinguished by single characters when all their representatives come to be known (that is, that upon a view of all the individuals the transitional differences are so gradual that hard and fast lines of distinction are obliterated); that genera and various other groups have descended, not from a single generalized genus, etc., of the same group, but from corresponding genera of one or more other groups—the doctrine of homologous groups; and that these homologous groups belong to different geological periods and different geographical areas, and are related to each other in a successional way like the epochs of geological time. To these are added the law of repetitive action, by which the structures of animals are shown to have originated from simple repetitions of identical elements; and the existence of a special force exhibiting itself in the growth of organic beings, called growth-force, or bathmism, the location of which at certain parts of the organism, indicating abstraction from other points, determines the direction of development. The location of the growth-force is accomplished by use or effort,