120. Electric cells of _Raia radiata_ 370 121. The Garden Bower-bird (_Amblyornis inornata_) 382 122. Courtship of Spiders 388 123. Courtship of Spiders (_continued_) 389 124. The Bell-bird (_Chasmorhynchus niveus_) 396 125. _C. tricarunculatus_ 397 SECTION I _EVOLUTION_ CHAPTER I. INTRODUCTORY. Among the many and unprecedented changes that have been wrought by Mr. Darwin's work on the _Origin of Species_, there is one which, although second in importance to no other, has not received the attention which it deserves. I allude to the profound modification which that work has produced on the ideas of naturalists with regard to method. Having had occasion of late years somewhat closely to follow the history of biological science, I have everywhere observed that progress is not so much marked by the march of discovery _per se_, as by the altered views of method which the march has involved. If we except what Aristotle called "the first start" in himself, I think one may fairly say that from the rejuvenescence of biology in the sixteenth century to the stage of growth which it has now reached in the nineteenth, there is a direct proportion to be found between the value of work done and the degree in which the worker has thereby advanced the true conception of scientific working. Of course, up to a certain point, it is notorious that the revolt against the purely "subjective methods" in the sixteenth century revived the spirit of _inductive_ research as this had been left by the Greeks; but even with regard to this revolt there are two things which I should like to observe. In the first place, it seems to me, an altogether disproportionate value has been assigned to Bacon's share in the movement. At most, I think, he deserves to be regarded but as a literary exponent of the _Zeitgeist_ of his century. Himself a philosopher, as distinguished from a man of science, whatever influence his preaching may have had upon the general public, it seems little short of absurd to suppose that it could have produced any considerable effect upon men who were engaged in the practical work of research. And those who read the _Novum Organon_ with a first-hand knowledge of what is required for such research can scarcely fail to agree with his great contemporary Harvey, that he wrote upon science like a Lord Chancellor.