File:Evolution and disease (1890) (14577533237).jpg

Identifier: evolutiondisease00blan (find matches)
Title: Evolution and disease
Year: 1890 (1890s)
Authors: Bland-Sutton, John, Sir, 1855-1936
Subjects: Diseases Medical genetics Abnormalities, Human Animals Disease Congenital Abnormalities
Publisher: New York : Scribner & Welford
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

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nvestiga-tion.1 Apart from such considerations, the view that thecentral nervous system is disposed around a modifiedpiece of intestine, offers an explanation of severalotherwise inexplicable phenomena which will be dulyconsidered in some of the ensuing chapters. Tails.—Among suppressed parts, so far as man isconcerned, must be included the tail. That man hasdescended from forms furnished with tails cannot bedoubted, for at the end of the vertebral column he stillcarries three, four, and occasionally five rudimentary 1 Those interested in this question will find the matter discussedin my monograph on Dermoids. Gaskells views are publishedin the Journal of Physiology. April, 1889, vol x. part 3. DISUSE AND ITS EFFECTS. 53 caudal or coccygeal vertebrae. The most constantnumber in the adult is three, but in the embryo germsof five vertebrae can be distinguished. This remnant ofa tail is connected with the sacrum by bands of fibroustissue, the degenerate remnants of the muscles which in
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Fig. 26.—An African child with a pendulous tumour hangingfrom its buttocks ; false tail. (After Virchow.) a functional tail raise, depress, or move it from side toside. This is not mere speculation, for these ligamen-tous bands are not infrequently replaced by musclesknown as curvator coccygis, extensor coccygis, andagitator caudae. The scepticism regarding the occur- 54 EVOLUTION AND DISEASE, rence of tails in men is mainly attributable to themistakes which have been made by incompetent ob-servers in reporting, as tails, structures which had noright to such a title, and it will be useful for us toconsider the various forms of true tails and the appen-dages which may be mistaken for them. We may, with Virchow, dividetails into two classes, true andfalse. True tails are of twovarieties : the most perfect tailsare composed of bony segmentsdirectly continuous with thevertebral column, as in the caseof monkeys, horses, dogs, cats,lions, &c. The less perfectvariety is like that of th

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