8/21 15--A SECTION OF AN INFLAMED LUNG SHOWING THE EXUDATE WITHIN THE AIR SPACES. Fig 15 is from the human lung, in which the air spaces are much larger than in the mouse.] The microscopic examination of any normal tissue of the body shows within it a variable number of cells which have no intimate association with the structure of the part and do not seem to participate in its function. They are found in situations which indicate that these cells have power of active independent motion. In the inflamed tissue a greatly increased number of these cells is found, but they do not appear until the height of the process has passed, usually not before thirty-six or forty-eight hours after the injury has been received. |