MARROW. 63 



nuclei, these cells contain but one large nucleus, which then usually 

 shows an appearance as of budding (b). Lastly, the existence of cells 

 within the marrow containing blood-corpuscles in various stages of 

 transformation into pigment, similar to those which occur in the spleen 

 pulp, has also been affirmed (by Osier). The marrow is very vascular, 

 the capillaries and veins being large and thin-walled ; indeed, according 

 to some authorities, the walls of the capillaries are imperfect, so that 

 there is an open communication between them and the interstices of 

 the tissue, and in this way it is supposed that the coloured blood-disks, 

 which are believed to be produced from the coloured nucleated cells of 

 the marrow, may get into the circulation. 



