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Show 10 THE DESCENT OF MAN. PART I. races differing so much that they must be classed as doubtful species? How are such races distributed over the world ; and how, when crossed, do they react on each other, both in the first and succeeding generations? And so with many other points. ~l_lhe enquirer would next come to the important point, whether man tends to increase at so rapid a rate, as to lead to occasional severe struggles for existence, and consequently to beneficial variations, whether in body or mind, being preserved, and injurious ones eliminated. Do the races or species of men, whichever term may be applied, encroach on and replace each other, so that some finally become extinct? \Ve shall see that all these questions, as indeed is obvious in respect to most of them, must be answered in the affirmative, in the same manner as with the lower animals. But the several considerations just referred to may be conveniently deferred for a time; and we will first see how far the bodily structure of man shows traces, more or less plain, of his descent from some lower form. In the two succeeding chapters the mental powers of man, in comparison with those of the lower animals, will be considered. The Bodily Structure of Man.-It is notorious that man is constructed on the same general type or model with other mammals. All the bones in his skeleton can be compared with corresponding bones in a monkey, bat, or seal. So it is with his muscles, nerves, bloodvessels and internal viscera. The brain, the most important of all the organs, follows the same law, as shewn by Huxley and other anatomists. Bischoff, 1 who is a hostile witness, admits that every chief fissure and fold 1 ' Grossbirnwindungen des Menschen,' 1868, s. 9G. CriAP. I. HOMOLOGICAL STRUCTURE. 11 in tbe brain of man has its analogy in that of the orang; but he adds that at no period of development do their brains perfect! y agree ; nor could this be expected, for otherwise their mental powers would have been the same. Vulpian 2 remarks: "Les differences reelles qui existent " entre l'encephale de l'homme et celui des singes supe': rieurs, sont bien minimes. II ne faut pas se faire H d'illusions a cet egard. L'homme est bien plus pres " des singes ant.hropomorphes par les caracteres anato': miques de son cerveau que ceux-ci ne le sont non" seulement des autres mammiferes, mais memes de " certains quadrumanes, des guenons et des macaques." But it would be superfluous here to give further details on the correspondence between man and the higher mammals in the structure of the brain and all other parts of the body. It may, however, be worth while to specify a few points, not directly or obviously connected with structure, by which this correspondence or relationship is well shewn. Man is liable to receive from the lower animals, and to communicate to them, certain diseases as hydrophobia, variola, the glanders, &c. ; and this fact proves the close similarity of their tissues and blood, both in minute structure and composition, far more plainly than does their comparison under the best microscope, or by the aiel of the best chemical analysis. Monkeys are liable to many of the same non-contagious diseases as we are; thus Rengger,3 who carefully observed for a long time the Cebus Azarm in its native land, found it liable to catarrh, with the usual symptoms, and which when 2 'Le9. sur la Phys.' 1866, p. 890, as quoted by M. Dally, 'L'Ordre des Primates et le Transformisme,' 1868, p. 29. 3 'Naturgeschichto der Sii.ugeth.iere von Paraguay,' 1830, s. 50. |