164 PRACTICAL MICROSCOPY. 



3. Nitrate of silver combines with the cement, forming albuminate 

 of silver, which becomes dark brown when exposed to light. 



If you have been successful, the silver will have penetrated the ten- 

 don, and mapped out the lymph channels, indicating an outline of 

 every lining cell by means of a dark border. Failure will result 

 only from non- attention to cleanliness in the handling of the tissue; 

 the silver in which case becomes deposited generally over the surface. 

 The margins or outlines of the cells, it must be remembered, are 

 stained with the silver. The nuclei may be demonstrated by after- 

 staining with dilute haema., or better, borax-carmine. The mounting 

 may be done in dammar, although the elastic fibres, of which the 

 matrix of the tendon is composed, will become stiff during immer- 

 sion, and show a tendency to curl and contract. If glycerin be used 

 after carmine staining, tissues should be washed thoroughly in water, 

 subsequently to the oxalic acid bath, transferred to equal parts of 

 glycerin and water, and allowed to remain for an hour, at least, before 

 mounting. 



CENTRAL TENDON OF THE DIAPHRAGM. SILVER 

 STAINING. (Vide Figs. 110, 111.) 



OBSEBVE: 

 (L.) 



1. The division of the specimen into dark and light areas. 

 (The dark areas represent the more solid portions of the tissue or the 

 partitions between the channels, and the light spaces are the lymph 

 paths.) 



2. The lymph paths the light spaces. (These show, with this 

 amplification, as irregular, winding, and anastomosing courses, 

 marked with very delicate lace-like tracery the silver lines.) 



3. Valves of the lymph paths. (At points, the paths will be 

 crossed by dark curved lines. These are imperfect valves, not unlike 

 a single cusp of an aortic valve. ) 



(H.) 



4. Outlines of the cells lining" the larger excavations (lymph 

 paths) in the tissue. (Note that the cells are generally elongate in 

 the direction of the lymph path. The edges are frequently serrated.) 



5. Stomata, minute openings at the junction of several cells. 



6. The construction of the valves. (These are curved against 

 the lymph flow, and covered with cells like other parts of the channeL 



