i60 Use oftHe Sutures in the Skulls of Animals. 



vessels may pass clown between them, free from compres- 

 won, and secrete the osseous n)attcr. At the same time, the 

 thin bones composing the upper part of the skull, resting as 

 an arch upon its basis, must be united together so firmly, as 

 not to be separated by common degrees of violence. For 

 this purpose, projecting points from the external surface of 

 each bone are reciprocally received into corresponding 

 niches ; which only penetrate through one half of the 

 thickness of the skull, and form an irregular kind of dove- 

 tailing. 



Two advantages arise from this structure being superficial, 

 and confined to the external table of the skull. The pro- 

 jecting points from each side, resting upon the solid surface 

 of the internal table of the opposite bone, caa resist more 

 effectually any violence which might tend to force the 

 bones inwards ; and the internal part of the skull presents, 

 by this means, a smooth surface tO' the coverings of the 

 brain ; for internally no- appeaiance of a jagged suture 

 is seen. 



From this view of the subject we see, that the sutures of 

 the human skull, by their peculiar formation, at once unite 

 the bones together, and so far separate them, as to allow the 

 interposition of a vascular organ by which their superficies 

 is gradually increased to its greatest extent.* This explana- 

 tion 



* Sinco tin's paper was written in the year ISOO, I have found, that a simi- 

 lar opinion wa'i published by Professor Soemmerring; in 1794, in his valu- 

 able work, " De corporis humani fabrica." To htm, therefore, any credit 

 which may belong to the primary suggestion of this use of the sutures is due. 

 As his opinion, however, has been little noticed by anatomists generally, and 

 Is placed in a clearer point of view by the facts which suggested this further 

 explanation of it to me; it has not been thought improper to give this essay a 

 place in these Memoirs. But whilst the reader will see, by the following 

 quotation, the near resemblance between the opinion of Professor Soemmer- 

 ring and that wliich I have brought forward, I hopetlie character of plagiarist 

 or compiler will not be attributed to me. 



" Usus horum sic sese habentium terminorum ossa cranii inter bene liquet. 



" Incrementum ambitus calvaria levant, ni enim inter ossa capitis moi post 

 partum suturx interponcrentur, ha:c crescere non posseut, nisi alia ratione 

 Datura rem inatitueret. Tali igitur modo incrementum calvarix cum incrc- 

 inento reliquorum ossium convenit ; initio enini suturis, vel potius lineis car- 

 tilaginosis ossa iis locis conglutinantur, verum tamen non nisi in cmbrionibu* 



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