170 STUDY OF INFLAMED TISSUES. 



the mucous membrane, and comminuting it in a drop of 

 glycerin with a blunt instrument. It need scarcely be added, 

 that both those cells of the deeper layers which are in the 

 natural state, and those which exhibit appearances of division, 

 have the ridged character. Similar changes can be studied in 

 certain chronic diseases of the skin, as in acuminated condy- 

 lomata. (See Chap. II.) 



Inflammation of Endothelium. As regards the endo- 

 thclium of the serous membrane, the changes consequent on 

 inflammation have been alreacty referred to. In the blood- 

 vessels, the inflammatory changes may be studied by cauter- 

 izing the external surface of any superficial vein (e. #., the ex- 

 ternal jugular or femoral), or even by simply ligaturing the 

 vessel. Three or four days after the injury, the vessel is ex- 

 cised and hardened in chromic acid, or treated with gold and 

 hardened in alcohol, for the preparation of sections. When 

 the vessel is very thin-walled, it can be studied at once, with- 

 out preparation, after straining with gold or silver. The 

 appearances correspond to those observed in the serous mem- 

 branes. 



Inflammation of Cartilage. Germination of the cells 

 of hyaline cartilage can be studied after mechanical injury of 

 articular cartilages. The best method is to pass a needle into 

 the knee-joint of a rabbit, in such a way that it penetrates into 

 the tibia. A few days after, sections are made of the fresh 

 cartilage, and stained in gold. It is more difficult to observe 

 inflammatory changes of the cartilage cells in the frog. Much 

 can be learnt from cartilages of human joints in a state of 

 chronic inflammation. 



Inflammation of Bone. Germination of the cells of bone 

 may be induced in the long bones of mammalia by passing a 

 red-hot needle as deeply as possible into a bone, previously 

 freed of the soft parts covering it, and then cauterizing the 

 hole with a pointed stick of nitrate of silver, or by violent 

 fracture. After a week or more the bone is excised. Scale- 

 like bits are then split off from the immediate neighborhood of 

 the injury, and steeped in chloride of gold, and then placed in 

 water acidulated with acetic acid till they are soft enough to 

 render it possible to make sections, which must be prepared 

 in glycerin. Another plan is to place the part in solution of 

 chromic acid (J to per cent.), to which hydrochloric acid has 

 been added, as described fully in Chap. II. The sections 

 should be so made as to comprise the transition between in- 

 flamed and normal conditions. Human inflamed bones can 

 often be studied in amputated limbs. In all of these cases the 

 lacuna? are seen to contain groups of young cells, instead of 

 the ordinary branched cells. 



