44 THE BONES. 



These variations have been noted in all the regions of the vertebral column^ 

 though they are rare in the cervical region. Sometimes they consist in a dimi- 

 nution, sometimes in an increase, in the number of the vertebrae, 



a. So far as it is known, a decrease in the number of the cervical vertebrae 

 in the domestic animals has not been observed. Goubaux has sometimes met 

 with eight cervical vertebrae, though, as the eighth offered relations with the first 

 rib, he was disposed to place it in the dorsal region. In this case the anomaly was 

 in the number of bones in the spine. 



b. The dorsal region is more frequently abnormal. Bourgelat and Rigot 

 have dissected Horses which had only seventeen dorsal vertebrse. Groubaux and 

 ourselves have seen similar instances, though the length of the animals afforded 

 no suspicion of modification in their spines. It is certainly more common to see 

 the mmiber of dorsal vertebrae increased to nineteen, as is proved by the observa- 

 tions of Bourgelat, Rigot, Husson, Goubaux, and our own. 



This increase is observed also in the asinine species. We have the skeleton 

 of an Ass in which there are twenty ribs on each side, and therefore twenty 

 dorsal vertebrae. In the Ox, fourteen dorsal vertebrae have been found. 



c. The lumbar region is still more frequently modified. The Horse at 

 times has only five lumbar vertebrae (Daubenton, Chauveau, Goubaux, Sanson, 

 and several German anatomists) ; the Ass only four (Goubaux). In the other 

 animals — the Dog, for example — an increase in number has been remarked ; 

 Girard has seen eight lumbar vertebrae, instead of seven. Goubaux and ourselves 

 have on several occasions seen seven lumbar vertebrae in the Sheep. 



d. The sacrum has often one or two pieces more in old subjects, due to 

 the fusion of the first or second of the coccygeal vertebrae with its posterior 

 extremity. At other times, the supernumerary piece is situated at the base. 

 Rarely is the number of sacral vertebrae diminished ; Goubaux has only met with 

 one instance in which there were four sacral vertebrae in the Horse. 



e. The nmnber of coccygeal bones is extremely variable ; and in order to 

 be convinced of this, one has only to look at the tables drawn up by anatomists. 

 Nevertheless, it is certain that the normal number is never less than seven or 

 eight, as Bourgelat stated in the first edition of his Anatomie. 



To resume, it is seen that all the regions of the spine may offer variations in 

 the number of vertebrae, and that these variations — rare between the neck and 

 the back — are, on the contrary, frequent at the two extremities of the lumbar 

 region. When the bones are deficient, the diminution is only apparent — that is, 

 the vertebra which is absent in one region is carried to the adjoining region. It 

 frequently happens, for instance, when a lumbar vertebra is missing, that the 

 sixth is united to the sacrum ; or when there are nineteen dorsal vertebrae, there 

 is one less in the lumbar region. It is not always sufficient to examine the 

 regions contiguous to the one which is modified, to gain an exact notion as to the 

 modification. In fact, a change in the number of vertebras in a region may be 

 compensated for by an alteration in a distant region. In the museum of the 

 Lyons school, there is the skeleton of an Ox in which there are fourteen dorsal 

 vertebrae, with the normal number of cervical, but only four sacral. We also 

 possess the skeleton of a Horse which has seven lumbar vertebrae, with the normal 

 number in the other regions, though the seventh bone is certainly the first sacral, 

 as it has all its characteristics ; and with regard to the fifth sacral bone, this 

 evidently comes from the coccygeal region. In the first skeleton, the increase 

 in the dorsal region has therefore been compensated for by a decrease in the sacral 



