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THE POPULAR SCIENCE MONTHLY.

is the whole notion of life having been originally "breathed" into one or more organic forms. Mr. Spencer's language is happily free from both these defects: he neither uses the phraseology of the Creative hypothesis, nor does he adopt a definition of biological "individuality," at variance with the Evolution philosophy. He distinctly teaches that living matter must have been at first formless, and that multiplication would have taken place, as among the lowest forms of the present day, exclusively by agamic methods—nay, more, he teaches that living matter must have been the gradual product or outcome of antecedent material combinations. "Construed in terms of evolution," he says,[1] "every kind of being is conceived as a product of modifications wrought by insensible gradations on a preexisting kind of being, and this holds fully of the supposed 'commencements of organic life,' as of all subsequent developments of organic life." But on the question whether the process of Archebiosis (life-evolution) is likely to have occurred once only, as Mr. Darwin seems to hint, or in multitudinous centres scattered over the earth's surface, Mr. Spencer makes no definite statement. The latter belief would, however, be entirely in accordance with his general doctrine; and we seem all the more entitled to infer that Mr. Spencer inclines to the notion of a multiple occurrence of Archebiosis, both in space and in time, since he does not reject the possibility of its occurrence in our own day. Granting "that the formation of organic matter and the evolution of life in its lowest forms may go on under existing cosmical conditions," he believes it "more likely that the formation of such matter and of such forms took place at a time when the heat of the earth's surface was falling through those ranges of temperature at which the higher organic compounds are unstable." But conclusions which we are only able to infer from the writings of Mr. Spencer have been distinctly enunciated by Mr. G. H. Lewes. In a criticism of the "Darwinian Hypothesis," he very forcibly pointed out that it is quite compatible with the hypothesis of evolution to admit a variety of starting-points for the formation of living matter, and he consequently laid down in principle a very important extension of the Darwinian doctrine, in its application to higher organisms. He says:[2] "Although observation reveals that the bond of kinship does really unite many divergent forms, and the principle of Descent with Natural Selection will account for many of the resemblances and differences, there is at present no warrant for assuming that all resemblances and differences are due to this one cause, but, on the contrary, we are justified in assuming a deeper principle which may be thus formulated: All the complex organisms are evolved from organisms less complex, as these were evolved from simpler forms: the link which unites all organisms is not always the common bond of heritage, but the uniformity of organic laws acting under uniform condi-

  1. "Principles of Biology," vol. ii., Appendix, p. 482.
  2. Fortnightly Review, 1868.