I understand the fascination exercised by this profound and ingenious conception, which is supported by immense knowledge, and ennobled by his loyal honesty. I should doubtless have yielded as so many others have done, if I had not long understood that all questions of this kind depend especially upon physiology. Now, my attention once aroused, I found no difficulty in recognising the point at which the eminent author quits the ground of reality and enters upon that of inadmissible hypothesis. I have thought it right to publish my criticisms upon the theory of transmutation, and upon Darwinism in particular. I was authorised to do so by the numerous attacks which have often been made, in no measured terms, against what I consider to be the truth, and against every opponent of the new theory. But while refuting theories I have always respected the authors and done justice to their work. I have quoted the good as well as the bad, and have always held aloof from the ardent and lamentable polemics raised by transmutation. I have had great pleasure, when occasion has offered, in defending the splendid researches made by Darwin in the natural sciences. For this very reason, and at the risk of being considered narrow minded, enslaved to prejudices and unable to leave an old groove, etc., etc., I consider myself entitled to attack Darwinism, if I employ none but the weapons of science. III. There are some points in Darwinism which are perfectly unassailable. We may consider as the most important the _struggle for existence_, and _selection_ which is the result of it. It is not the first time, certainly, that the former has been established, and the important part it has to play in the general harmony of the world has at least been partly comprehended. I will here only recall to the mind of my readers the fables of La Fontaine. But no one had insisted, as Darwin has done, upon the enormous disproportion which exists between the number of births and the number of living individuals; no one had investigated, as he has, the general causes of death or of survival which produce the final result. By pointing out the fact that each species tends to increase in number in geometrical progression, which is proved by the number of offspring to which a single mother can give birth during the whole course of her life, the English naturalist makes it easy to comprehend the intensity of the struggles, direct or indirect, which are undergone by animals and plants against one another and the surrounding world. It is, most certainly, entirely owing to this struggle for existence, that the whole world, in a few years, is not overrun by some species, or the rivers and ocean filled in the same manner.