86 
VERTEBRAL COLUMN. 
growing, and of being reproduced after injury, like any other 
part of the living tissue ; being copiously supplied with blood¬ 
vessels, which penetrate into their interior. These bones give 
support, and afford points of attachment, to the soft parts, in the 
limbs (where they exist) as well as in the trunk; but the former 
are not unfrequently wanting, as in Serpents: and we must look 
in the trunk, therefore, for that peculiar arrange¬ 
ment which is characteristic of this division of 
the Animal Kingdom. The back-bone, as it is 
commonly termed, is found in all Vertebrated 
animals; though in a few among them (the 
lowest Fishes) it is very imperfect (§ 53). It 
consists of several pieces jointed together, so as 
to possess great flexibility; whilst they are so 
firmly connected by ligaments, that they cannot 
easily be torn asunder or displaced. The number 
of these pieces varies considerably; in Man there 
are only 33 ; in some long-tailed Mammals there 
are more than 70; but in many Serpents there 
are several hundred. Each of them is termed a 
vertebra; and the whole structure, composed of the 
Fig. 26.—VERTE- un ited vertebrae, is termed the vertebral column 
bral qlumn. 26). The ordinary character of the vertebrae 
is, that each is perforated by an aperture, which, united to the 
corresponding apertures of those above and below it, forms 
a continuous canal; and in this canal, one of the most im¬ 
portant parts of the nervous system, the spinal 
cord (commonly but erroneously termed the spinal 
marrow), is contained. The solid portion of the 
vertebra (fig. 27, a) is termed its body; and the 
projections, b and c, are termed its processes , the 
former spinous , the latter transverse. The row 
a of spinous processes forms the ridge which we 
Fi V ertebra GLE P ass i n g down the back; it is seen on the 
right-hand side of fig. 26. To the transverse 
processes the ribs are attached. The vertebral column is ex¬ 
panded (as it were) at its upper extremity, to form the skull ; 
in the large cavity which it contains, the brain is lodged; and 
its bones are so arranged as to give protection to the organs of 
sense also. At the opposite extremity we see it contracted 
into the tail; which is composed of a series of vertebrae 
