258 



extreme limits, which may be considered to include all differences of 

 bony configuration apart from those of very considerable rarity. 



Naturally the greatest number of cases presenting differences 

 from what is shortly to be defined as the normal condition show but 

 slight variation from that form. In the ordinary dissecting course 

 these would be passed by as exhibiting no characters worthy of note. 

 It is only by complete maceration after dissection that these minor 

 variations will attract attention. 



But the knowledge gained from a study of the recent parts may 

 be applied to the macerated skeleton with considerable profit and 

 assurance, and thus some information may be gathered regarding 

 associated conditions of vessels and nerves which probably stand as 

 dominant factors in the configuration of the skeleton. 



In a series of forty skeletons examined without previous selection, 

 twenty-seven presented practically the same characteristic features. 

 These applied not only to tiie appearance of the first rib but also to 

 the lower cervical and upper dorsal vertebrae, and of these more 

 especially to the seventh cervical and first dorsal. 



For the present we are concerned only with the ribs; considera- 

 tion of the vertebral characteristics may be postponed. 



But it must be clearly understood that no bone exhibits morpho- 

 logical features which are without relation to the characters of neigh- 

 bouring parts of the skeleton. The skeleton is developed as a whole 

 and its features cannot be studied by reference to its separate seg- 

 ments. The study of a single bone is incomplete if no reference is 

 made to those in intimate association with it. 



Having stated this axiom, reference iuay be made to the ribs 

 alone, the vertebrae being by no means neglected but the considera- 

 tion of their associated features omitted at the moment for the sake 

 of greater clearness. Among the forty skeletons mentioned, the 

 twenty-seven to which attention has first been called, presented the 

 following characters. The markings were somewhat ill-defined in the 

 region of the sulcus sub-claviae. Although the groove was very rudi- 

 mentary in but five of the twenty-seven, in no case was it of such 

 a character as to indicate definitely whether it had been produced by 

 artery or nerve. On careful inspection of these five cases it was found 

 that the sulcus subclaviae was usually better marked on the left side and 

 that its general direction and the bevelling of the inner border indicated 

 that the artery had been the dominant factor in its production. 



