THE HUMAN STERNUM 35 



His main morphological thesis is diametrically opposed to the view 

 at present advanced. He considers the sternum as made up of a series of 

 intercostal segments corresponding to vertebral bodies ; and the absence of 

 centres in the lower segments as indications of reductions (from below 

 up). He does not, however, depend for his proof upon segmental ossification. 

 This, he admits, cannot be maintained, but he relies on transient cleavages 

 in the cartilaginous sternum {Rippen linieri), which, he says, occur opposite 

 the costal attachments. But one would submit that prior to these cleavages 

 (which cannot be said to be, by any means, constant or obvious) the cartila- 

 ginous model is a longitudinal strip without, at an earlier period, any trace 

 of a metameric structure, either in cartilage or before the formation of 

 cartilage, that has yet been satisfactorily demonstrated. The segmental 

 character appears to be introduced by the association of the ribs with this 

 sternal anlage. The only obvious cleavage is at the manubrio-sternal 

 junction ; and that in the foetal sternum is by no means constant in 

 occurrence or definite in time. 



