Page:Popular Science Monthly Volume 15.djvu/25
CLEWS IN NATURAL HISTORY.
Darwin's theory does not demand that the gorilla or any of his compeers should be directly connected with man. The gorilla with his nearest relation lives, so to speak, at the top of his own branch in the great tree of life, while man exists at the top of another higher and entirely different bough. The connection between the human and low r er types is made theoretically to exist at some lower part of the stem when, from a common ancestor, the human and ape types took divergent roads and ways toward the ranks of nature's aristocracy. But although in some cases the need for "missing links" is seen, even theoretically, to be non-existent, or at least of a widely different nature from that supposed by the popular mind, there are yet cases in which that need is very apparent, and wherein, through the persistent tracing of the clews nature has afforded, the past history of more than one race of animals and plants has been made plain and apparent. Of such clews which are really mere traces, and nothing more there are no better examples than the curious fragments of structures found in many animals and plants, and named "rudimentary organs." An animal or plant is thus found to possess a mere trace of an organ or part which, so far as the highest exercise of human judgment may decide, is of not the slightest utility to the being. It is invariable in its presence, and as fixed in its uselessness. It bears no relation to the existing life or wants of the animal, but may in some cases as, for example, in a certain little rudi- mentary pocket in man's digestive system, serving as an inconvenient receptacle for plum-stones and like foreign bodies prove a source of absolute disadvantage or even danger. On what theory can the pres- ence of such organs and parts be accounted for? is a question of ex- tremely natural kind. The replies at the command of intelligent humani- ty are but two. Either the animal was created with the useless append- age in question a supposition which includes the idea that Nature, after all, is somewhat of a bungler, and that nothing further or more com- prehensible than the fiat "It is so," can be said on the subject or, secondly, we may elect to explain the puzzle by the assertion that the "rudimentary organ" of the existing animal represents a part once fully developed in that animalVremote ancestors, but now
Dwindled to the shortest span.
The rudimentary organ or appendage is represented in the animal of to-day as a legitimate heritage derived from its ancestor. It is, in short, a family feature, to which the animal is the "rightful heir," but which has fallen through the operation of natural laws and conditions into disuse and desuetude, and has accordingly suffered with the career of living nature "down the ringing grooves of change." Necessarily, this second and rational explanation of the rudimentary appendages of ani- mals and plants is founded on the supposition that nature and nature's creatures are continually undergoing alterations, and that they have been modified in the past, as they will be in all time to come. The ex-