MARROW. Ill 



that they are essentially of the same nature, if indeed 

 the one is not to be regarded as derived from the 

 other. 



Other cells may perhaps he met with much fewer 

 in number, flattened in form, and sometimes branched, 

 with a large clear oval nucleus, and in some instances 

 containing yellowish -red pigment granules. They 

 are larger than the proper marrow-cells, and exhibit 

 no changes of form. They appear to be connective 

 tissue-corpuscles. There is yet another element to 

 be found in the marrow most likely to be met with 

 in a bit taken from near the inner surface of the bone. 

 This is the rnyeloplaque or ostoclast, and is charac- 

 terized by its enormous size whence the name giant 

 cell by its granular appearance, and by containing 

 a number of clear round or oval nuclei grouped 

 together in the middle of the cell, or, in some cases, 

 a single large irregular nucleus with numerous buds 

 from its circumference. 



Preparation 12. To isolate these various ele- 

 ments of the marrow better than can be done in the 

 fresh condition, a piece of the tissue is to be placed 

 in weak spirit (ordinary methylated spirit diluted 

 with twice its bulk of water) for a day or two. 

 After this time a small portion is thoroughly broken 

 up with needles in a drop of water on a slide, is then 

 covered, and stained by allowing dilute logwood 

 solution to flow in under the edge of the cover-glass. 

 The logwood is replaced in a minute or two by water, 

 and this again by glycerine. By this means a per- 

 manent preparation is obtained, which can be studied 

 at leisure, and which very well exhibits the different 

 kinds of cells above enumerated, whilst the red 

 blood-corpuscles are rendered almost completely in- 

 visible. 



