THE STERNUM : ITS EARLY DEVELOPMENT AND OSSIFICATION. 27 



The part of the sternum between the attachments of the sixth 

 and seventh costal cartilages is cartilaginous at birth, and the 

 question of its ossification is deferred for the present. It 

 appears that it may be ossified by extension from the fourth 

 piece, though there is reason for believing that in some cases at 

 least it may possess a separate and independent centre. 



(C) Fissures : Grooves : Foramina. — One remarkable negative 

 feature characterises the series of foetal sterna examined. In 

 all there is a complete median plate of cartilage, grooved it may 

 be on one or both sides, perforated in some instances by one or 

 more holes, but in no single instance is there a fissura sterni. 

 A longitudinal groove (Table III.) is characteristic of the foetal 



Table III. — Grooves. 



meso-sternum, occurring in 158 out of 222 examples, or 70'1 per 

 cent., a proportion which obtains generally for all ages. It may 

 be faint or obvious ; it may be found on one or both aspects of 

 the meso-sternum, and implicate it in the whole or part of its 

 length, but it never appears in the pre-sternum. This grooving 

 of the meso-sternum is probably associated with the method of 



