occupied but a fraction of the time devoted to pigeons: over twenty works are quoted for historical facts, skeletons of various rabbits were prepared and exhaustively compared, the effects of use and disuse of parts traced, most careful measurements are given, and a list of the modifications which domestic rabbits have undergone, with the probable causes, concludes the chapter. As to pigeons, no pigeon-fancier ought to be without the book, for never assuredly was a sporting topic treated by so great a thinker and so admirably. The numerous experiments in crossing different breeds, and the results obtained, make this one of the most instructive books for all breeders. It would seem desirable that this portion of the book should be issued in a separate form. Again, when we turn to the sections on plants we see how indefatigable Darwin was, for he tells us that he cultivated fifty-four varieties of gooseberries alone, and compared them throughout in flower and fruit.

The chapters on Inheritance, and on Reversion to ancestral characters, or atavism, are profoundly suggestive. What can be more wonderful, the author asks, than that some trifling peculiarity should be transmitted through a long course of development, and ultimately reappear in the offspring when mature or even when old? Nevertheless, the real subject of surprise is not that a character should be inherited, but that any should ever fail to be inherited. Gradually leading up to the important hypothesis with which the work closes, he observes that to adequately explain the numerous characters that reappear after intervals of one or more generations, we must believe that a vast number of characters, capable

of evolution, lie hidden in every organic being. "The fertilised germ of one of the higher animals, subjected as it is to so vast a series of changes from the germinal cell to old age-incessantly agitated by what Quatrefages well calls the tourbillon vital-is perhaps the most wonderful object in nature. It is probable that hardly a change of any kind affects either parent, without some mark being left on the germ. But on the doctrine of reversion the germ becomes a far more marvellous object, for, besides the visible changes to which it is subjected, we must believe that it is crowded with invisible characters, proper to both sexes, to both the right and left side of the body, and to a long line of male and female ancestors separated by hundreds or even thousands of generations from the present time; and these characters, like those written on paper with invisible ink, all lie ready to be evolved under certain known or unknown conditions."

Through a further discussion of many deeply interesting facts about the intercrossing of breeds and species, and about the causes of variability, we pass to the hypothesis of pangenesis, which, briefly stated, supposes that the cells or units of the body are perpetually throwing off minute granules or gemmules, which accumulate in the reproductive system, and may, instead of developing in the next generation, be transmitted in a dormant state through more than one generation and then be developed. Combination in various degrees between these gemmules is supposed to influence their appearance or non-appearance in the offspring at various stages.

This hypothesis certainly gives a picture of a possible

mode of accounting for many peculiarities shown by living organisms. Although not generally accepted, it has certainly not been disproved. Mr. Grant Allen's opinion that it is Darwin's "one conspicuous failure," and that it is "crude and essentially unphilosophic," must be discounted by his known devotion to Mr. Herbert Spencer's philosophy. If Darwin had been a specialist in modern physiology, he might, perhaps, have expressed his hypothesis in a more persuasive form; but Weismann's germ plasma theory is the only alternative one hitherto suggested in place of it.

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CHAPTER VII.

LTHOUGH the descent of man from animal ancestors was directly implied in the "Origin of Species," Darwin hesitated at the time of its publication to declare his views fully, believing that he would only thus augment and concentrate the prejudice with which his theory would be met. He had for many years held the views he afterwards expressed; but it was not until he had by his other works raised up a strong body of scientific opinion in favour of his great generalisation, that he fully presented his views on man to the public. The "Descent of Man" was studied as a special case of the application of his general principles, a test all the more severe because several classes of argument were necessarily cut off, such as the nature of the affinities which connect together whole groups of organisms, their geographical distribution, and their geological succession. But adopting the high antiquity of man as demonstrated, he considered in detail the evidence as to man's descent from some preexisting form, the manner of his development, and the value of the differences between the so-called races of man. No originality is claimed for the theory or for the facts advanced; but it may safely be affirmed that

the master's acuteness, his moderation, his candour, and his desire to state facts which tell against him, are as conspicuous in the "Descent of Man" as in any of his works.

The "Descent of Man," which was published in 1871 in two volumes, with numerous illustrations, began, after a short introduction, with a suggestive series of questions, which to the evolutionist suffice to decide the question as to man's origin. As the answers to these questions are obvious, Darwin first concentrated his inquiry upon two points on which disputes must necessarily occur, namely, the traces which man shows, in his bodily structure, of descent from some lower form, and the mental powers of man as compared with those of lower animals. The facts of our bodily structure are inexplicable on any other view than our community of descent with the quadrumana, unless structure is but a snare to delude our reason. It is only our natural prejudice, says Darwin, and that arrogance which made our fathers declare that they were descended from demigods, which leads us to demur to this conclusion.

The comparison of the mental powers of animals with those of man, proving, as Darwin contends, that they therein also show traces of community of descent, was certain to provoke much more debate, for the term "instinct" and the use made of it by naturalists and psychologists as signifying untaught, unlearnt ability, largely tended to obscure the question, and to create prejudices against believing that instincts could be built up by inherited experience, that instincts were really not absolute and fixed, but relative and variable, and that all instincts