IV. The development of the vertebral column in mammals, as illustrated by its development in Mus musculus

Abstract

The research work to be described was carried out upon the suggestion of Prof. E. W. MacBride. Some justification for it may be found in the prevailing dual conception of the mode of development of the vertebral column in mammals, since notwithstanding the researches of Remak (1851), Rosenberg (1876), Froriep (1886), Weiss (1901), Bardeen (1905), Barge (1915) and others, opposing views are held as to whether or not the vertebrae of mammals are segmental structures. The work of Froriep maintains that they are; that of Weiss, Bardeen and others that they are not. The aim of the present investigation is to attempt to impart some finality to the argument and to settle the controversy that exists concerning the relation between the sclerotomes and the membranous and cartilaginous incipient vertebrae with the intervertebral accessorial structures. An attempt has been made to indicate the nature of the modifications effected in the region of the atlas and axis, and special consideration has been given to the so-called pro-atlas. In addition, the nature and number of the occipital segments have been observed, and the part played by these in the formation of the occipital region of the cranium has received attention.