OF THE MEDULLARY TISSUE OF THE BONES. 141 



171. Duverney* has made it the subject of several ob- 

 servations: Grutzmachert and IsenflamJ have given detailed 

 descriptions of it. Every osteologist, and all those who have 

 paid attention to the adipose tissue, have also occupied them- 

 selves with the medulla. Havers, particularly, has well de- 

 scribed and figured its vesicular texture. Albinus has a beau- 

 tiful plate of it in his Jlnnotationes Academicx, the vessels 

 however are represented too large: Mascagni in his Prodromo 

 has also given a good figure of the medulla. 



172. The marrow occupies the great medullary cavity of 

 the bodies of the long bones, the cellular cavities of the short 

 ones, of the extremities of the long bones, the thickness of the 

 wide bones, and even the pores of the compact subtance of the 

 bones. It is totally deficient in the sinuses and aerial cells of 

 the bones of the cranium. 



173. Thefatwhich occupies the medullary canal of thebones 

 represents a cylinder moulded by the bony parietes of this ca- 

 nal, and is contained in a membrane called the internal or medul- 

 lary periosteum. This membrane, whose very existence some 

 have denied, while others considered it as being formed of 

 two layers, is composed of one single leaf, easily perceived 

 by an experiment, which consists in sawing a bone and ex- 

 posing it to fire or plunging it in acid : the membrane becomes 

 crisp, is detached from the bone and forms a distinct canal 

 whose tenuity is such, that without this precaution it is almost 

 impossible to see it. Its tissue can only be compared to that 

 of a cobweb. This membrane lines the interior of the bone 

 and appears to continue on to their extremities with the mar- 

 row that fills them. It sends off prolongations into the com- 

 pact substance and furnishes inside an infinitude of similar 

 parts, whose disposition, in general, resembles that of the 

 filaments and lamina that compose the cellular membranes. 



* Memoires de PJlcademie des Sciences, 1700. 



j- De ossium medulla. Lips. 1754. 



t Ueber das Knockenmark, in beitrsege, &e. Von Isenflamm und Rosen- 

 muller B. II., Leipzig-, 1803. 



Clopton Havers. OsteoL Nov. Lond. 1691. et Obs. nov. de ossibut. 

 Amstel. 1731. 



