OP THE MEDULLARY TISSUE OP THE BONES. 145 



peculiar compound is thus formed, a kind of stucco* that has 

 no resemblance to bone. Haller and other physiologists have 

 also thought that the marrow served for the reproduction of 

 bone, and the formation of callus particularly. Observation, 

 however, shows us, that fractures heal so much the more 

 readily as the patient is young, and the less marrow there is, 

 or the less fat the marrow contains. Duverney, and others, 

 have considered the marrow as necessary to the nutrition of 

 the bones; is a sufficient proof of the inadmissibility of this 

 opinion, that many animals have none, as birds, and that deer's 

 horns are deprived of it, that this fluid does not exist in in- 

 fancy, and that the bones are formed before the marrow. The 

 marrow has also been regarded as the reservoir of latent calo- 

 ric, and of electricity. Marrow does not serve to lubricate 

 articulating surfaces, for the synovia exists in many places 

 where there is no marrow. 



179. The marrow undergoes some morbid changes.* 

 While the bone is consolidating in fractures, the fat disappears 

 in the medullary canal; the cellular tissue of this canal becomes 

 compact, as in other cases of solution of continuity, and ends 

 in ossification : this last fact, observed by Bichat, has since been 

 verified by several observers, when the consolidation is per- 

 fect, the medullary membrane re-assumes its properties. 



After amputation, the same phenomena are observed in the 

 marrow, as in other wounds, affecting the fatty tissue : the oily 

 matter disappears, and a cellular and vascular layer is formed 

 at the truncated extremity of the bone which finally closes. 

 The marrow is destroyed in the sequestra, and does not appear 

 to be re-established after they are taken out; at least it has ne- 

 ver been known so to do; perhaps the state of the parts has 

 never been examined a sufficient length of time after the ter- 

 mination of the disease. 



The medullary membrane is susceptible of inflammation: 

 it is probable to this and its consequences, that internal necro- 

 sis is to be attributed. It is equally probable, that pains in the 

 bones depend on this inflammation. A peculiar induration of 



* See Moignon. Teutamen de morbis ossium medullas. Paris et Lugtf. 

 Ann. iii. 



