THE SKELETON 33 



Of special interest, however, are the variations of the separate 

 divisions of the vertebral column, in relation to other parts of 

 the skeleton which have become secondarily attached to it, such 

 as the ribs and the pelvic girdle. These variations, though 

 effected ontogenetically, have a phylogenetic significance, and 

 may therefore be described in further detail. 



Although the pre-sacral portion of the column consists normally 

 of twenty-four vertebrae, Embryology and Comparative Anatomy 

 show that this cannot be regarded as a primitive condition, and 

 that the pelvis formerly lay much farther back than at present, 

 that is, that the trunk was originally longer than now. (We 

 shall see later that a more extensive body-cavity or coelom was 

 connected with this greater length of the vertebral column.) 



Eosenberg has demonstrated that in the course of human 

 development the first sacral vertebra becomes incorporated in 

 the sacrum later than the second, and that later than the third, 

 and so on. And further, since a primary relationship between 

 the vertebrae which become the two anterior coccygeal of the 

 adult and the developing sacrum is discoverable, it is evident 

 that while new sacral articulations are formed anteriorly, detach- 

 ment of vertebrae which were formerly sacral takes place 

 posteriorly, the latter being transformed into coccygeal vertebrae. 1 

 A forward shifting of the sacrum and pelvic girdle is thus onto- 

 ' genetically proved. 



attention to the detailed differences in the condition of the lumbar vertebrae of the 

 European and certain dark-skinned races, and the anthropoid Apes.] 



[Cunningham has shown (Mem. B. Irish Acad., No. II. 1886) that Aeby's denial 

 of the existence of a lumbar curvature in the Gorilla is untenable. His own test for 

 a lumbar curvature is a line drawn from the centre of the anterior border of the 

 upper surface of the first lumbar vertebra to the centre of the anterior border of the 

 lower surface of the last lumbar vertebra. The distance of the most prominent 

 point on the ventral surface of the lumbar section of the column from this line, 

 multiplied by one hundred and divided by the length of the line, gives the index 

 of curvature.] Little is known concerning the lumbar curvature of the savage 

 races of mankind ; but the cousins Sarasiu, on the examination of dried" skeletons 

 of the Veddahs of Ceylon, report the lumbar vertebrae to be distinctly concave 

 anteriorly. [From what has been said above, it would appear more than probable 

 that the application of the Cunningham method to the study of the Veddah back- 

 bone, in the fresh or specially prepared state, would reveal a lumbar curvature accord- 

 ing to the above, its most recent and" rigid, definition. And, from what is known of 

 the backbones of other races (ex. the Australian), it would appear probable that 

 the observation of the Sarasins is rather indicative of a greater suppleness of the 

 column during life, induced by habitual resort to certain postures, such as squatting, 

 which lead to a greater compression of the vertebrae, and a corresponding greater 

 tendency towards obliteration of the curvature after death.] 



1 Distinct indications of a shifting of the pelvic girdle are traceable in the lower 

 animals also, such shifting being in some cases in a proximal and in others in a distal 



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