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Updated: May 26, 2025
Rudimentary organs may be utterly aborted; and this implies, that we find in an animal or plant no trace of an organ, which analogy would lead us to expect to find, and which is occasionally found in monstrous individuals of the species. In tracing the homologies of the same part in different members of a class, nothing is more common, or more necessary, than the use and discovery of rudiments.
There is no great biologist now living who does not accept the essentials of the doctrine of descent. Five lines of proof may be offered in support of Darwin's theories, and it may be well for us, as students of sociology, briefly to review these. The homologies or similarities of structure of different animals. There are very striking similarities of structure between all the higher animals.
In the great class of molluscs, though we can homologise the parts of one species with those of other and distinct species, we can indicate but few serial homologies; that is, we are seldom enabled to say that one part or organ is homologous with another in the same individual.
Of course there is no exact parallelism between the birth, growth, and death of species in the animal world, and the birth, growth, and death of societies in the world of man. Yet there is a certain parallelism. There are strange analogies; it may be that there are homologies.
Serial homologues so formed might be called, as Mr. Ray Lankester has proposed, "homoplastic." But there are, it is here contended, abundant reasons for thinking that the predominant agent in the production of the homologies of the limbs is an internal force or tendency.
In one point, however, we must own that he seems slow of apprehension or limited by preconceived opinions, in his reception of the homologies pointed out by Oken and the Physiophilosophical observers. In the same range of intellects we should reckon Linnaeus and Humboldt, and should have reckoned Goethe, had he given himself to science.
Rudimentary organs may be utterly aborted; and this implies, that we find in an animal or plant no trace of an organ, which analogy would lead us to expect to find, and which is occasionally found in monstrous individuals of the species. In tracing the homologies of the same part in different members of a class, nothing is more common, or more necessary, than the use and discovery of rudiments.
He would explain the serial homologies of such creatures as the lobster and centipede thus: Animals of a very low grade propagate themselves by spontaneous fission.
The unchecked ingenuity of speculative anatomists proved itself fully competent to spin any number of contradictory hypotheses out of the same facts, and endless morphological dreams threatened to supplant scientific theory. Happily, however, there is a criterion of morphological truth, and a sure test of all homologies.
In considering the embryological structure of man, and the homologies he therein presents to the lower animals, Mr. But Mr. Darwin's pronominal "we," in this connection, admits of qualification. He can hardly speak for all the scientific world at once.
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