154 SKELETON. 



tige of its existence. Occasionally, indeed, we find the latter 

 to have occurred in one or more sutures, even before the age 

 of puberty, as I have repeatedly witnessed of the sagittal, the 

 squamous, and the lambdoidal sutures. 



The manner in which the sutures are formed is sufficiently 

 interesting: they are generally said to be made by the radii of 

 ossification, from the opposite bones meeting and passing each 

 other, so as to form a serrated edge. This explanation may 

 account partially for the shape of the edge of the sutures, but 

 not for their invariable position; inasmuch as we always find 

 the sutures in the same relative situation, and having the same 

 course. If they depended exclusively on so mechanical a pro- 

 cess, as the rays of one bone shooting across the rays of ano- 

 ther by their own force, we ought to find, occasionally, the sa- 

 gittal suture more on one side of the head than on the other, 

 and not straight, because in some instances ossification is a 

 more rapid process on one side than on the other. Moreover, 

 in all cases where bones arise from different points of ossifica- 

 tion, and meet, the serrated edge should be formed; and parti- 

 cularly in the flat bones. Observation, however, proves that 

 the os occipitis, which is formed originally from four points of 

 ossification, and therefore has as many bones composing it in 

 early life, does not present these bones afterwards united by the 

 serrated edge. The acromion process of the scapula, though 

 originally distinct from the spinous, never unites to it by suture, 

 but always by fusion. The mode of junction in the three bones 

 of the sternum is always by fusion. In short, the observation 

 holds good in numerous other instances. 



Berlin and Bichat, reject fully the mechanical doctrine con- 

 cerning the sutures, and present one founded upon reason and 

 observation, and susceptible of confirmation by any accurate 

 observer. The dura mater and the pericranium, before, ossifica- 

 tion commences, form one membrane consisting of two laminas. 

 Partitions pass from one of these laminae to the other, which 

 mark off the shape, or constitute the mould of the bones long 

 before they are perfected. The peculiar shape of the bony 

 junction, or, in other words, of the sutures or edges of the bones 

 in adult life, depends, therefore, exclusively upon the original 

 shape of the partitions. When the latter are serrated, the points 



