I divide, then, morbid anatomy into two great parts. The first contains the history of the alterations common to each system, whatever may be the organ in the structure of which it is concerned, or whatever may be the place it occupies. It is necessary to show at first the different alterations of the cellular, arterial, venous, nervous, osseous, muscular, mucous, serous, synovial, glandular, cutaneous textures, &c. to examine the kind of inflammation, suppuration, gangrene, &c. peculiar to each; to speak of the different enlargements of which they are susceptible, the changes in their nature, which they undergo, &c. Some, as the mucous, the cutaneous, the serous, the glandular, &c. afford in this respect an immense field to morbid anatomy. The others, as the fibrous, the nervous, the muscular, &c. are more rarely changed in their texture. We shall see hereafter that nutrition alone is performed in these, and that the others are particularly the seat of exhalation, absorption, secretion, &c. functions which suppose much energy in the insensible contractility and organic sensibility, which are connected with all the alterations of texture. After having thus pointed out the alterations peculiar to each system, in whatever organ it is found, an examination should be made of the diseases peculiar to each region; as those of the head, the chest, the abdomen, and the extremities, after the common method. Here they may be divided, 1st. into diseases which can especially affect an organ as a whole, and not one of its textures alone, which is very rare. 2d. Into the characters peculiar to each portion of this or that texture; for example in the head, the peculiar symptoms which are seen in diseases of the serous surface of the tunica arachnoides, those in affections of the mucous surface of the pituitary membrane, &c. This course is incontestably the most natural, though, as in all divisions in which we wish to copy nature, there are many cases which it almost excludes.