"You can now understand how, by such means and an inexhaustible diversity of circumstances, nature, with sufficient length of time, has been able to and should produce all these results. "If I should choose here to pass in review all the classes, orders, genera, and species of animals in existence I could make you see that the structure of individuals and their organs, faculties, etc., is solely the result of circumstances to which each species and all its races have been subjected by nature, and of habits that the individuals of this species have been obliged to contract. "The influences of localities and of temperatures are so striking that naturalists have not hesitated to recognize the effects on the structure, the developments, and the faculties of the living bodies subject to them. "We have long known that the animals inhabiting the torrid zone are very different from those which live in the other zones. Buffon has remarked that even in latitudes almost the same the animals of the new continent are not the same as those of the old. "Finally the Count Lacépède, wishing to give to this well-founded fact the precision which he believed it susceptible, has traced twenty-six zoölogical divisions on the dry parts of the globe, and eighteen over the ocean; but there are many other influences than those which depend on localities and temperatures. "Everything tends, then, to prove my assertion--namely, that it is not the form either of the body or of its parts which has given rise to habits and to the mode of life of animals, but, on the contrary, it is the habits, the mode of life, and all the other influential circumstances which have with time produced the form of the bodies and organs of animals. With new forms new faculties have been acquired, and gradually nature has arrived at the state where we actually see it. * * * * * "Finally as it is only at that extremity of the animal kingdom where occur the most simply organized animals that we meet those which may be regarded as the true germs of animality, and it is the same at the same end of the vegetable series; is it not at this end of the scale, both animal and vegetable, that nature has commenced and recommenced without ceasing the first germ of her living production? Who is there, in a word, who does not see that the process of perfection of those of these first germs which circumstances have favored will gradually and after the lapse of time give rise to all the degrees of perfection and of the composition of the organization, from which will result this multiplicity and this diversity of living beings of all orders with which the exterior surface of our globe is almost everywhere filled or covered?