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the same nature with that, which constitutes the animal basis of the 

 bones themselves. 



Towards the latter periods of life, the quantity of cartilage be- 

 tween the edges of the bones is gradually diminished by the progress 

 of ossification ; and the osseous substance of one bone, at last, be- 

 comes continuous with that of those, with which it is articulated. 

 By this means all appearance of the articulations is removed, first 

 on the internal surface, and afterwards on the external; and, if 

 death did not put a stop to the progress of ossification, it would only 

 terminate, when it had formed the whole cranium into one bone. 



For a considerable period after birth, the bones of tlie cranium 

 are very thin, and their structure uniform. By degrees their thick- 

 ness increases, and their surfaces becoming very compact, while the 

 interior assumes a cellular appearance, what are called the tables and 

 diploe of these bones are formed ; but, in very advanced life, the 

 texture of these bones becomes uniformly compact, and the cellular 

 tissue is obliterated. Hence the existence of tables and diploe is 

 peculiar to the middle period of life, and are not be found well 

 marked either in the very young or very aged subject. 



Read Feb. 22, 1819. 



