Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct - for the use of schools and colleges (1870) (14779579111)

Identifier: outlinesofcompar00agas (find matches)
Title: Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct : for the use of schools and colleges
Year: 1870 (1870s)
Authors: Agassiz, Louis, 1807-1873 Gould, Augustus A. (Augustus Addison), 1805-1866 Wright, Thomas, 1809-1884
Subjects: Physiology, Comparative Zoology
Publisher: London : Bell & Daldy
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library



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s erect, as monkeys,bears, sloths, and many rodents, it is proportionally larger thanin other mammals. On the concave anterior surface of the sacrumwe observe holes (4) for the passage of the nerves ; and on itsposterior surface (fig. 120), similar apertures (11, 11, 11) forthe same purpose are seen. Fig. 119 is a profile of this bone. (§ 258. The COCCYX consists of four small bones, which re-tain only a rudimentary centrum, and are soldered together inman (fig. 119, 2.) These bones are, in fact, the rudiment of anorgan, the tail, which attains great importance and dimensionsin some animals, as shown in the comparative table (§ 260). (§ 259. The VEETEBE.E are firmly united together by pro-cesses of bone (fig. 114—116, 2 and 3) that lock into each other.Bet ween every two vertebrae, an elastic fibro-cartilaginous cushion K2 132 SPINAL COLUMN. is interposed. By this arrangement the chain of bones isconverted into a strong elastic central axis, more or less move- Fig. 121. Fig. 122.
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m different animals, ac-cording to the general struc-ture and habits of each. Fig. 121 exhibits a frontview of the spinal column ofman. It is of a pyramidalform, the base of the pyramidrests upon the sacrum, andthe apex supports the skull.We observe, likewise, that thediameter of the bodies of thevertebrae differs in differentregions, being broad in theneck, narrow in the back,and broad again in the loins. Fig. 122 represents a pos-terior view of the spinal co-lumn. The different forms ofthe neurapophyses, in the cer-vical, dorsal, and lumbar re-gions, are here shewn. Theyare observed to project back-wards and a little downwardsin the neck ; they lie obliquelydownwards in the back, andstand backwards in the loins.On each side of the neuralspines, a groove is seen formedby a junction of the arches ofall the vertebrae ; boundedinternally by the neural&pmes,and externally by the para-popliyses ; in this groove themuscles are lodged that im-part motion to the column. Fig. 1 23 is a la