The descent of man and selection in relation to sex / by Charles Darwin.

  • Charles Darwin
Date:
1889
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Licence: Public Domain Mark

Credit: The descent of man and selection in relation to sex / by Charles Darwin. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

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    two sexes of many mammals. So that the correspondence in general structure, in the minute structure of the tissues, in chemical composition and in constitution, between man and the higher animals, especially the anthropomorphous apes, is ex- tremely close. Embryonic Development.—Man is developed from an ovule, about the 125th of an inch in diameter, which differs in no respect from the ovules of other animals. The embryo itself at a very early period can hardly be distinguished from that of other members of the vertebrate kingdom. At this period the arteries run in arch-like branches, as if to carry the blood to branchiae which are not present in the higher vertebrata, though the slits on the sides of the neck still remain (/, <j, fig. 1), marking their former position. At a somewhat later period, when the extremities are developed, the feet of lizards and mammals, as the illustrious Von Baer remarks, the wings and feet of birds, no less than the hands and feet of man, all arise from the same fundamental form. It is, says Prof. Huxley,14 quite in the later stages of development that the young human being presents marked differences from the young ape, while the latter departs as much from the dog in its developments, as the man does. Startling as this last assertion may appear to be, it is demonstrably true. As some of my readers may never have seen a drawing of an embryo, I have given one of man and another of a dog, at about the same early stage of development, carefully copied from two works of undoubted accuracy.'6 After the foregoing statements made by such high autho- rities, it would be superfluous on my part to give a number pi borrowed details, shewing that the embryo of man closely resembles that of other mammals. It may, however, be added, that the human embryo likewise resembles certain low forms when adult in various points of structure. For instance, the heart at first exists as a simple pulsating vessel; the excreta are voided through a cloacal passage; and the os coccyx projects 14 ' Man's Place in Nature,' 1863, magnified, the embryo being twenty- n 67. five days old. The internal viscera 15 The human embryo (upper have been omitted, and the uterine ap- fig.) is from Ecker, 4 Icones Phys.,' pendages in both drawings removed. 1851-1859, tab. xxx. fig. 2. This I was directed to these figures by embryo was ten lines in length, so Prof. Huxley, from whose work, ihat the drawing is much magnified. ' Man's Place in Nature,' the idea of The embryo of the dog is from giving them was taken. Hiickel has Pischoff, ' Entwicklungsgeschichte also given analogous drawings in his des Hunde-Eies,' 1845, tab. xi. fig. ' Schopfuiigsgesehiehte.' ♦2 B This drawing is five times
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