Professor Roscoe, again, approaching the subject from the chemical point of view, says, speaking of red blood corpuscles, ‘We have not been able, and the evidence at present rather goes to show that there is not much hope of our being able, to construct these granules artificially; and the question is in this position, that so far as science has progressed at present we have not been able to obtain any organism without the intervention of some sort of previously existing germ.’ 229. If we assume the truth of this principle it appears to lead us directly to infer that life is not merely a species of energy, or a phenomenon of matter. For we have seen (Art. 103) that the great characteristic of all energy is its transmutability—its Protean power of passing from one form to another. We may no doubt produce large quantities of electricity by means of an electrified nucleus, but we can do the same without any such nucleus—we can make unlimited steel magnets by the help of one piece of loadstone, but we can do this even more effectually by means of a galvanic battery—we may produce fire from a spark, but we can obtain it without a spark. Life, however, can be produced from life only, and this law would seem to give an indication that the solution of the mystery is not to be found by considering life as merely a species of energy. It is some time since we gave up the idea that life could generate energy; it now seems that we must give up the idea that energy can generate life. 230. In preceding chapters we have given our readers a sketch of the methods according to which men of science imagine that evolution has been carried out in the universe of energy and in that of life. In both worlds the principle of Continuity requires that in endeavouring to account for the origin of phenomena we shall not resort to the hypothesis of separate creations, that we shall not pass over from the conditioned to the unconditioned; and Darwin, Wallace, and their followers have, as we have shown, endeavoured to prove that processes still pursued by nature are sufficient in a great measure, if not entirely, to account for the present development of organised existence without the necessity of resorting to separate creations. Darwin especially imagines that all the present organisms, including man, may have been derived by the process of natural selection from a single primordial germ. When, however, the backward process has reached this germ, an insuperable difficulty presents itself. How was this germ produced? All really scientific experience tells us that life can be produced from a living antecedent only; what then was the antecedent of this germ? Hypotheses have no doubt been started, but we cannot regard them in any other light than as an acknowledgment of a difficulty which cannot be overcome. We appear to have reached an impenetrable barrier similar to that which stood in our way when we contemplated the production of the visible universe. And precisely