That there should be physiological units possessed of the power attributed to them, harmonizes with what has recently been put forward by Dr. H. Charlton Bastian; who maintains that under fit conditions the simplest organisms develop themselves into relatively large and complex ones. This is not supposed by him to be due to any inheritance of ancestral gemmules, but to direct growth and transformation of the most minute and the simplest organisms, which themselves, by all reason and analogy, owe their existence to immediate transformation from the inorganic world.
Thus, then, there are grave difficulties in the way of the reception of the hypothesis of Pangenesis, which moreover, if established, would leave the evolution of individual organisms, when thoroughly analysed, little if at all less mysterious or really explicable than it is at present.
As was said at the beginning of this chapter, "Pangenesis" and "Natural Selection" are quite separable and distinct hypotheses. The fall of one of these by no means necessarily includes that of the other. Nevertheless, Mr. Darwin has associated them closely together, and, therefore, the refutation of Pangenesis may render it advisable for those who have hitherto accepted "Natural Selection" to reconsider that theory. [Page 220]
Review of the statements and arguments of preceding chapters.--Cumulative argument against predominant action of "Natural Selection."--Whether anything positive as well as negative can be enunciated.--Constancy of laws of nature does not necessarily imply constancy of specific evolution.--Possible exceptional stability of existing epoch.--Probability that an internal cause of change exists.--Innate powers must be conceived as existing somewhere or other.--Symbolism of molecular action under vibrating impulses.--Professor Owen's statement.--Statement of the Author's view.--It avoids the difficulties which oppose "Natural Selection."--It harmonizes apparently conflicting conceptions.--Summary and conclusion.
Having now severally reviewed the principal biological facts which bear upon specific manifestation, it remains to sum up the results, and to endeavour to ascertain what, if anything, can be said _positively_, as well as negatively, on this deeply interesting question.