BY DR. KLEIN. 61 



edges of the cells are sharply defined, their substance is clear, 

 or beset with a veiy few granules, their nuclei are also .some- 

 what granulous. At all depths the intercellular sub stance 

 (ground substance or matrix) can be seen, under high powers. 

 to be divided into territories, each corresponding to a eel: 

 long as the preparation is fresh, most of the cells completely 

 fill the cavities which they occupy in the matrix ; these cavi- 

 ties are termed capsules. Only here and there can a clear 

 space be distinguished between the external surface of the cell 

 and the wall of the capsule. For the most part each cell 

 contains a single nucleus; there are, however, some which 

 contain two nuclei. In the middle part of the preparation 

 they are found either singly and at equal distances from eacli 

 other, or in pairs, i. e., two in one capsule, united by straight 

 lines of contact. Occasionally two cells are seen placed 

 together in the same relative position to each other as the two 

 inclosed in the same capsule, but separated by a septum of 

 ground substance, so that each is inclosed in its own cavity. 

 If, for the indifferent fluid, we substitute distilled water, the 

 cartilage cells separate themselves from the internal surface of 

 the cavity, while their protoplasm becomes turbid. If the 

 cartilage of the newt is subjected to the induction current in 

 the manner already described, a sudden shrinking of the cell 

 results, in consequence of which it assumes a coarsely granular 

 appearance, and a nodulated form, while the nucleus becomes 

 invisible. This condition is permanent, the cell never resum- 

 ing its former appearance ; in some, however, the nucleus 

 becomes more or less invisible. A perfectly similar change is 

 produced by the addition of dilute acetic acid. In many parts 

 of the preparation, especially near the margin, where the 

 cartilage cells are closely packed, the change does not take 

 place. The cells become more transparent, while their edges 

 and those of the nuclei become more sharply defined. 



Sections can be easily made of cartilage in the recent state, 

 and can then be examined in an indifferent liquid. The con- 

 dyles of the tibia or femur of a frog or mammal may be used 

 or the costal cartilages of the latter. The greatest variety is 

 found in different cartilages, and in different parts of the same 

 cartilage, in respect of the number and size of the cells. For 

 making permanent preparations of cartilage, the chloride of 

 gold method is better than any other. Thin fresh sections of 

 cartilage are placed for ten or fifteen minutes in a half per 

 cent, solution of chloride of gold, exposed to light in distilled 

 water for twenty-four hours or more, and then mounted in 

 glycerine. The matrix remains clear, or is only very slightly 

 stained violet, while the corpuscles display all transitions of 

 color between violet, violet-red, and dark red. The nuclei are 

 usually brightly stained, of a reddish tint. The method 



