such cases may be illustrated by the very common accident of the severance of the end of a human finger at the root of the nail. If the incision is far enough back to remove the whole of the vessels which secrete the horny substance that forms the nail, there will be no after growth of anything resembling a nail. If some of those vessels are left in the stump, there will be continuous secretion and deposit of the horny substance, which may go so far as to form a crude resemblance to a nail. But if all the vessels which constitute the means of perpetuating a perfect nail are not left in their normal number and action, there can be no such thing as the formation of a new nail. Whether it is correct to speak of the imperfect continuation of a few of the vessels to secrete the substance which it is their normal function to secrete, as a "power of regeneration," is more than doubtful, if by such a power is meant a power to make a new and complete structure to take the place of the structure that has been cut away. It is nothing more than the continued action of a few vessels, less in number than the normal system required for the continued growth and renewal of the part in question. The abortive product in such cases looks like an unsuccessful effort of Nature to make a new structure in place of the old one; but it is not in reality such an effort. The fact that the same thing occurs, in just the same way and to a corresponding extent, in different animals, has no tendency to prove anything excepting that these different animals share the same general system of secreting vessels for the formation and perpetuation of the several parts of their structures. It has no tendency to prove that they are co-descendants from a common ancestral stock, for on the hypothesis of their special and independent creation a common system of secreting vessels would be entirely consistent with their peculiar and special constructions. FOOTNOTES: [35] "Descent of Man," pp. 164, 609. [36] "Descent of Man," p. 159. [37] "Origin of Species," p. 148. [38] "Descent of Man," p. 165. [39] "Descent of Man," p. 158. [40] "Descent of Man," p. 155. [41] Ibid. [42] "Descent of Man," pp. 156, 157. [43] Ibid., p. 156. [44] "Descent of Man," p. 156. [45] "Descent of Man," p. 6. [46] Ibid., p. 8. [47] Ibid. [48] "Descent of Man," pp. 9, 10, quoting Huxley, "Man's Place in Nature," p. 65. [49] "Descent of Man," p. 11 _et seq._ [50] Ibid. [51] "Descent of Man," p. 24. Consult Mr. Darwin's note on Prof. Bianconi's explanation of homologous structures upon mechanical principles, in accordance with their uses. [52] Mr. Herbert Spencer's peculiar views are not here included in the discussion, but they will be considered hereafter.