CARTILAGE. 17 



This substance stains the nuclei of the cells a light pink colour. It possesses no advantages 

 over the methods already indicated. 



The advanced student may study the action of chloride of gold and nitrate of silver on 

 hyaline cartilage. 



Action of Chloride of Gold. Place in a one per cent, solution of chloride of gold for half an 

 hour the articular end of the femur of a frog newly killed. Wash it thoroughly to remove the 

 surplus gold, and place it in water acidulated with a few drops of acetic acid, and expose it to 

 the light until the gold is reduced usually for twenty hours or until the cartilage becomes 

 of a beautiful violet tint Make thin sections of the cartilage, and mount them in Farrant's 

 solution. 



EXAMINATION (H). Observe the cells arranged in several planes and stained of a 

 deep violet colour. They usually fill the lacunae completely. Often two cells may be seen 

 together, in such relationship as to suggest that they have been produced by the division or 

 ' fission ' of a single cell. The matrix is stained of a lighter colour. 



Action of Nitrate of Silver. Silver the articular cartilage of the femur of a freshly killed frog, 

 as directed at p. xlv, and after exposure to light, and when it has become brown, make a thin 

 slice and mount it in Farrant's solution. Cover. 



EXAMINATION (H). Observe the matrix stained brown, but the cells are not stained, 

 they, are merely represented by oval or round clear spaces, which correspond exactly in shape 

 and distribution with the cartilage-corpuscles. The silver has not affected the cells, though it 

 has darkened the intercellular substance. The gold effect represents the positive, this the 

 negative effect. Staining with logwood reveals the presence of a cell in each apparently 

 empty space. 



ARTICULAR CARTILAGE. 



Make a number of vertical sections of the head and subjacent bone of the femur or 

 other long bone of a cat or other animal, decalcified according to the methods indicated (p. 

 15), preferably by a or c. 



(a) Osmic Acid. Place sections in a one per cent, solution of osmic acid for twenty-four 

 hours. Wash and mount in glycerine jelly (p. xlviii), for Farrant's solution renders the section 

 too transparent. 



EXAMINATION (L). If the femur be chosen, observe the general arrangement of the 

 parts from the articular surface downwards. The superficial cells are flattened, and they always 

 are parallel to the surface and at right angles to the axis of pressure. A little below the 

 surface they are in irregular clumps of twos and threes, and deeper down near the bone they 

 are in rows, parallel to the long axis of the bone. These rows are produced by transverse 

 cleavage of the cells. Below the cartilage is the bone. The cartilage is divided into two 

 zones, distinctly mapped off from each other by the character of the matrix. Across the sec- 

 tion, about two-thirds or half-way below the articular surface of the cartilage, there runs a line 

 slightly wavy. All that lies superficial to this has a hyaline matrix, and what lies below it, i.e. 

 as far as the bone, is more or less granular and less transparent. In this lower part the matrix 

 is calcified. This calcified part is distinctly mapped off from the subjacent bone ; a well-marked 

 wavy line with very distinct undulations the one part dovetailing into the other, indicating 



D 



