Observe the itch, herpes, cancer, venereal disease, &c. when they have ceased to be local affections, they spread themselves universally; they alternately attack different textures, according to the relation which they have with the organic sensibility of these textures. But it is almost always separately that they attack them; an organ is never as a whole influenced by them in all its parts. What do I say? If two of these diseases exist at the same time, one seizes upon one texture, the other upon a different one of the same organ. Thus the stomach, the intestines, the lungs, &c. can be attacked by two different diatheses, and each will be independent of the other, because each will be fixed upon a different texture, one upon the mucous, for example, the other upon the serous, &c. Let us not, however, exaggerate this independence of the textures of the organs in diseases, lest experience should contradict us. We shall see that the cellular system is oftentimes a medium of communication, not only from one texture to another in the same organ, but from one organ to a neighbouring one. Thus in many chronic diseases, all the parts of the same organ are gradually changed, and at the examination of this organ after death, the whole of it appears to have been affected, though one of its textures only was so at first. In the cancer of the breast, you find at first only a small gland that rolls under the finger; finally the glandular, the cellular, and even the cutaneous textures are confounded in one common cancerous mass. Cancer of the stomach, the intestines, the penis, &c. follows the same course. Observe phthisis, exhibiting in the beginning some small tubercles in the pulmonary texture, at length invading oftentimes the pleura, the bronchial membrane, &c. How little soever you may examine bodies with a view to the same chronic disease, and at different periods, you will be convinced of the truth of this assertion, viz. that a texture being at first affected in an organ, communicates its affection gradually to others, and that you will be deceived in judging of the primitive seat of the disease, if you attempt to determine it from the parts found affected at the time of the examination. In acute diseases, continuity is oftentimes sufficient to explain the different symptoms that appear in textures that are not affected. The peritoneal coat only being inflamed, vomiting is produced. We cough and sometimes expectorate considerably when the pleura alone is diseased. Delirium comes on when the tunica arachnoides is inflamed, though the intellectual functions are not connected with it. Frequently the diseases of the pericardium are sufficient to disturb the motion of the heart, &c. We cannot deny after this, that oftentimes an alteration in one of the textures alone of an organ is sufficient to disturb the functions of all the others; but still it is in one only, that the primitive source of the evil exists.