1 88 PRACTICAL HISTOLOGY. [XIV. 



normal saline tinged with methyl-green, aldehyd-green, or aniline- 

 green. The marrow will fall as a precipitate. Examine a little of 

 this in normal saline. Stain some in picro-carmine, and mount in 

 dihite glycerine. 



(H) Observe the various forms of marrow and other cells met 

 with, the nuclei tinged red. The large myeloplaxes with numerous 

 nuclei have their protoplasm green and the nuclei red. The fat-cells 

 are quite green. 



(ii.) Place some of the red marrow for 12-24 hours in dilute 

 alcohol, mount and stain the cells with picro-carmine. In this way 

 the nuclei of all the cells are stained red, their protoplasm yellowish, 

 while nucleoli are revealed. 



(iii.) Harden some of the red marrow in Hayem's fluid for 

 twenty-four hours. Wash the deposit, stain (picro-carmine) and 

 mount a little in glycerine. This is a good hardening medium for 

 this purpose ; the red blood-corpuscles can be readily distinguished, 

 while the nuclei in all the cells are distinct. 



6. T.S. Red Marrow. Small pieces of the ribs of a young 

 rabbit are placed in the following fluid for one day : 



Sodic sulphate . . . 2.5 grams. 



Mercuric chloride . . 0.25 ,, 



Water . . . 500 cc. 



Rinse in water, and transfer to picric acid to decalcify the bone. 

 The tissue can then be soaked in gum, then hardened in alcohol 

 and sections cut. Sections may be stained with eosin and logwood. 

 The eosin stains any cells containing haemoglobin of a reddish-orange 

 tint. 



ADDITIONAL EXERCISES. 



7. Cover-Glass Preparation of Red Marrow (H). As described for blood, 

 get a thin layer of red marrow on a cover-glass and stain it for twenty-four 

 hours in Biondi's fluid (p. 140). Dry cover-glass preparations may also be 

 stained with methylene-blue, eosin-harnatoxylin. or methyl-green. Mount 

 the cover in xylol-balsam. If desired, clear it up with oil of cloves in which 

 a little eosin is dissolved, and remove the clove-oil by xylol. This method 

 yields excellent preparations. 



8. Squeeze on a slide a little of the red marrow from the rib of a young 

 rabbit. Squeeze a little between two cover-glasses to get in a thin film, find 

 expose the latter for a minute or two to the vapour of osmic acid. Stain it 

 with picro-caruiine and mount it in glycerine. 



