SPECIAL CONNECTIVE TISSUES. 61 



then be readily cut in thin sections with a razor. The process is as 

 follows; 



To four ounces of the dilute chromic-acid solution add a drachm of 

 0. P. nitric acid. The bone, previously divided into slices not over 

 one-fourth cf an inch in thickness, is then placed in the fluid, and 

 should be completely decalcified in a week or ten days. Examine the 

 pieces after twenty-four hours by puncturing with a needle. Should 

 the action proceed too slowly, add a few drops more of the nitric acid 

 from time to time. The bone eventually takes on a green color. 

 After complete decalcification, wash the pieces for twenty-four hours 

 in clean water, and preserve them until required, in " B " alcohol. 

 Small pieces of young bone may be decalcified in a saturated aqueous 

 solution of picric acid. The process is slow, but it leaves the tissue 

 in excellent condition. 



Sections cut in the usual way may be stained with carmine and 

 picric acid, and examined in a drop of glycerin. They should not 

 after the staining be placed in the oil of cloves, as they would curl and 

 become hard. Transfer them to equal parts of glycerin and water, 

 from which they are to be carried to the slide. Add a drop more of 

 the dilute glycerin if necessary and put on the cover-glass, carefully 

 avoiding air bubbles. If you desire to make a permanent mounting, 

 the edge of the cover must be cemented to the slide. 



Thoroughly wipe the slide, around the cover, with moistened 

 paper, until every trace of glycerin is removed. Then with a sable 

 brush, paint a ring of zinc cement (vide formulas) around the slide 

 just touching the edge of the cover-glass. Repeat the cementing in 

 twenty-four hours. A turn-table will be a useful aid in this work. 

 Dr Carl Heitzmann, who uses glycerin as a universal mounting fluid, 

 prefers ordinary black (asphalt) varnish as a cement. 



SPECIAL CONNECTIVE TISSUES. 



Connective Tissue of the Lymphatic System. The matrix of lym- 

 phoid or adenoid tissue consists of a network of branching cells, 

 which support the lymph corpuscles. It is distributed extensively 

 in organs, and where it appears in stained sections, the lymphoid 

 cells are so numerous as to obscure the reticulum almost entirely. The 

 structure will be minutely described in connection with the lym- 

 phatic system. 



The Connective Tissue of the Central Nervous System (neuroglia) 

 consists of branched connective-tissue cells, which are supported in 



