ANATOMY OF THE BOXES. 483 



demonstrated the presence of stellate cells, or corpuscles, 

 exactly filling up the lacunae, and sending prolongations into 

 the canaliculi. 1 These structures have since been studied 

 by Rouget, who has succeeded in demonstrating them in 

 fresh bones from the foetus, without using any reagent. 2 

 They are stellate, granular, with a large nucleus and several 

 nucleoli, and are of exactly the size and form of the lacunae. 

 They send out prolongations into the canaliculi, but it has 

 been impossible to ascertain positively whether or not they 

 form membranes lining the canaliculi through their entire 

 length. 



Marrow of the Bones. The peculiar -structure called 

 marrow is found in the medullary cavities of the long bones, 

 filling them completely and moulded to all the irregulari- 

 ties of their surface. It is also found filling the cells of the 

 spongy portion. In other words, with the exception of the 

 vascular canals, lacunaB, and canaliculi, the marrow fills all 

 the spaces in the fundamental substance. We know very 

 little of the functions of the marrow, and will therefore pass 

 it over with a brief description. 



It is now settled that the cavities of the bones are not 

 lined with a membrane corresponding to the periosteum, and 

 that the marrow is applied directly to the bony substance. 

 In the foetus and in very young children, the marrow is red 

 and very vascular. In the adult it is yellow in some bones, 

 and gray or gelatiniform in others. It contains certain pecu- 

 liar cells and nuclei, with amorphous matter, adipose vesi- 

 cles, connective tissue, blood-vessels, and nerves. 



Medullocells. Robin has described little bodies, existing 

 both in the form of cells and free nuclei, called medullocells. 

 These are found in greater or less number in the bones at 



, Cellular Pathology, Philadelphia, 1863, p. 112. Virchow's first 

 observations were made in 1850. 



2 ROUGET, Note sur les corpuscles des os. Journal de la physiologic, Paris, 

 1858, tome i., p. 764, etseq. 



