54:6 ^SE OF THE SUTUUKS. 



place in every bone of the cranium, it is probable that even 

 after the whole of the brain is incafed in bone, the addition 

 is flill made at the edge of each, and that the general enlarge- 

 ment originates where they are all mutually joined by the 

 futures. Of this procefs I had a very ftriking iliuftration fome 

 years ago. In a young fubjeft, from what caufe I know not, 

 the depofition of ofleous matter had been fuddenly increafed 

 a fl)ort time before death. It was in different ftages of pro- 

 grefs, but had taken place in all the bones of the body which 

 Inffance in the I preferved ; in fome partially, in others generally. In all, 

 the new ofieous matter was elevated above the level of the 

 bone upon which it was placed. In fome parts of the pa- 

 rietal bones it was only in its commencement, and put on the 

 appearance of a net-work, fimilar to that which may be ob- 

 ferved in the fame bones at an early period of their formation. 

 In other parts the methes of the net- work were more or lefs 

 filled up ; in others again completely, fo as to put on the uni- 

 form appearance of folid bone. The fame reticulated appear- 

 ance was evident on the edges of all the bones of the fkull, 

 where they form the futures, and at the extremities of the cy- 

 lindrical bones, between the body and epiphyfis. The fame 

 appearance of increafed depofition was feen on the furface of 

 the cylindrical bones, with this difference, that the methes 

 were not circular, but oblong fquares ; fo as to put on more 

 of the ftriated appearance. In fome parts, the newly fe- 

 creled bone was eafily feparable from the general mafs, and 

 formed a thin layer externally, affording one of the beft proofs 

 I have met with, of the increafe of cylindrical bones in thick- 

 nefs by depofition externally, whilft a correfponding internal 

 abforption goes on. From the flriking fimilarity of appear* 

 ance on the furfaces and edges of the bones, we may fafely 

 conclude, that the fame procefs of depofition was going on in 

 both, and may thence infer, that the bones of the flcuU are 

 increafed in extent bythe depofition of offeous matter at their 

 edges, or where they are joined to each other by future. This 

 fa6l points out to us, in a great meafure, the real ufe of this 

 peculiar mode of jun6lion. 



In order that the bones of the fkull may be increafed in ex- 

 The ferrated tent, it is necellary that they fliould be retained at a certain 



nlr &r ^""' ^'^^"P^ ^^^^ ^^^^ ^^^^^' ^^^^ ^^^ periofleum with its veffels 

 2 may 



