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No case of Agamogenesis is known in which, WHEN A DIFFERS WIDELY FROM B, it is itself capable of sexual propagation. No case whatever is known in which the progeny of B, by sexual generation, is other than a reproduction of A. But if this be a true statement of the nature of the process of Agamogenesis, how can it enable us to comprehend the production of new species from already existing ones?
It is obvious, from these extracts, that Professor Kölliker's hypothesis is based upon the supposed existence of a close analogy between the phænomena of Agamogenesis and the production of new species from pre-existing ones. But is the analogy a real one? We think that it is not, and, by the hypothesis, cannot be. For what are the phænomena of Agamogenesis, stated generally?
How then is the production of new species to be rendered intelligible by the analogy of Agamogenesis?
How then is the production of new species to be rendered intelligible by the analogy of Agamogenesis?
It is obvious, from these extracts, that Professor Kolliker's hypothesis is based upon the supposed existence of a close analogy between the phenomena of Agamogenesis and the production of new species from pre-existing ones. But is the analogy a real one? We think that it is not, and, by the hypothesis, cannot be. For what are the phenomena of Agamogenesis, stated generally?
Let us suppose Hyænas to have preceded Dogs, and to have produced the latter in this way. Then the Hyæna will represent A, and the Dog, B. The first difficulty that presents itself is that the Hyæna must be asexual, or the process will be wholly without analogy in the world of Agamogenesis.
In favour of this hypothesis, Professor Kolliker adduces the well-known facts of Agamogenesis, or "alternate generation"; the extreme dissimilarity of the males and females of many animals; and of the males, females, and neuters of those insects which live in colonies: and he defines its relations to the Darwinian theory as follows:
Let us suppose Hyaenas to have preceded Dogs, and to have produced the latter in this way. Then the Hyena will represent A, and the Dog, B. The first difficulty that presents itself is that the Hyena must be asexual, or the process will be wholly without analogy in the world of Agamogenesis.
Let us suppose Hyaenas to have preceded Dogs, and to have produced the latter in this way. Then the Hyaena will represent A, and the Dog, B. The first difficulty that presents itself is that the Hyaena must be non-sexual, or the process will be wholly without analogy in the world of Agamogenesis.
No case of Agamogenesis is known in which, 'when A differs widely from B', it is itself capable of sexual propagation. No case whatever is known in which the progeny of B, by sexual generation, is other than a reproduction of A. But if this be a true statement of the nature of the process of Agamogenesis, how can it enable us to comprehend the production of new species from already existing ones?
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