PATHOLOGY 379 1COUS ^pi- adventitious tissue on the surface, the pattern of which is deter mined by the looping or den driform branch ing of the blood vessels (fig. 43). These formative aberrations of secretion are apt to return after removal, even al though the con ditions which gave rise to them are obviated ; the new development and persistence of the blood- a ""cous polypus pear to be the occasion of recur- Fio. 43. Portion of a dendriform papilloma or wart (horse); rence in these blood-vessels run in the central stem and in the branches of fibrous tissue, cases. Mucous Polypi. In many cases mucous polypi have an un doubted connexion with those states of the mucous membranes which are included under catarrh. An approximation to a multiple polypous condition may be found in the stomach subject to long standing catarrh, where the ridges and furrows of the mucous mem brane amount to an actual polyiwsis ventriculi. Multiple polypi are sometimes met with also in the intestine. The commonest seats of the isolated and stalked mucous polypus are the nasal passages and the cervix uteri. Their structure is after the same plan as the more epidermic papilloma, everywhere tu bular mucous glands, the epithelium of which is wonderfully perfect (fig. 44) ; these may branch or communi cate more than do the normal gland- tubes of the part, and they are separated by tracts of connective tissue which appear to the naked eye as dendriform white lines. In these morbid products the line is definitely crossed from functional to formative, but we cannot assume any other force than the indwelling secretory activity of the part ; the unique fact that presents itself here is that a perversion of that force gives rise to an organ-like new forma- FlG - 44 -~ tion whose plan of structure is plainly determined by the blood-vessels. It is worthy of note that the bronchial mucous membrane, which is the most liable to catarrhs, has practically no liability to mucous polypi ; and the bronchial mucosa is distinguished, not only by its investment of cartilaginous rings and plates, but by the density of its elastic and muscular coats. Single Glandular Tumour (Adenoma). As the mucous polypus andular is characteristic of the wide expanse of mucous membrane, so the mour. simple glandular tumour or adenoma is the formative result of functional disorder in the definitely bounded epithelial organs with racemose systems of ducts. The glands that are most liable to this condition are the breast, the salivary glands (including the buccal and labial), the lacrymal glands, and the skin -glands in certain regions. Whenever the more uniform expanses of glandular struc ture, such as those of the stomach and the intestine, take on a formative activity to the depth (instead of to the surface, in the form of polypi), the result is a cancer, involving other considerations besides those primary or direct deviations from the secreting activity which we are now considering. Intra-canalicular Papilloma. The simple or non - cancerous tumour-disease of glands may be represented in most cases in the ularpa- light of deviations from the normal secretory activity, deviations illoma. which take a formative direction. They connect not remotely with catarrhal states of the secreting structure ; but, speaking generally, they stand for irregularities of the apparatus and process of secretion which transcend the notion of catarrh. It will be convenient, however, to proceed in the analysis of them from that familiar basis. The nearest approach to the effects of catarrh is shown in the folded or uneven state of the wall of the terminal secreting recesses or acini of a gland ; this condition may be ob served in certain skin-glands and in the breast. The cut (fig. 45) is taken from a tumour of the skin-glands of the dog. The lining of columnar or cubical epithelial cells, which is ordinarily a perfectly even surface, is raised into distinct papillary eminences. These may even meet across the space, changing its interior into a nearly solid or at least trabecular tissue. The next cut (fig. 46) shows precisely the same process in the breast, this time not in an acinus but in a mple itra- inal- duct ; the result is what is called an " intra-canalicular papilloma," FIG. 45. Papillary outgrowths of epithelial lining in a tubu lar gland. FIG. 40.- -Intra-canalicular papilloma of breast. and it is not different in its origin and nature from the papillomata of expanded mucous surfaces which we have already considered. Cartilaginous Tumours of Glands. Another formative result of Dis- disordered function, which takes us quite beyond the limits of ordered catarrhal effects, is the occupation of the walls and interior of the glandu- acinus, not with papillae of the lining epithelium nor with the lar func- epithelial cells shed into the free space as solid by-products oftionspro- the secretion, but with a new tissue foreign to the gland. This ducing occurs in the mamma (more often in the dog than in man), in the cartilage, salivary glands (parotid, submaxillary, and labial), in the lacrymal gland, and in skin-glands (e.g., of the scalp) ; the new tissue may be of the mucous or myxomatous kind, and it is not rarely carti laginous, or even osseous, at a few points in the midst of the car tilage. The occurrence of myxomatous and cartilaginous areas is common in the parotid tumours of man and in the mammary tumours of the dog, and it is usually explained as an arbitrary and unaccountable overgrowth and transformation of the support ing connective tissue of those organs. It remains to inquire whether it may not be brought into a rational connexion with disorder of the proper secretory func tion. The cut (fig. 47) is taken from a case of extensive tu mour-disease in the mamma of the bitch, in which much cartilage had J^*^ formed. It J*% v t- represents se- ^f^/FY" veral acini of the gland, hav ing their in terior occupied with large spherical or oval vesicu lated cells with FIG. 47. Group of acini of mamma (dog), occupied in part firm hvaline with large vesiculated hyaline cells which are practically contents.There cartilaginous. can be no question that these are epithelial cells strangely changed ; but the change will not seem so strange if we keep in mind the range of transformation which the secreting cells of the breast are nor mally liable to. There is a stage in the unfolding of this gland from its periodical state of rest in which the cells become vesicles filled with mucus, just as there is a more mature period when they are still vesicles but filled with a more fatty or milk -like fluid. The change in the tumour is, after all, only from the mucus -filled vesicles to vesicles occupied by a firm hyaline sub stance ; and, if it were connective -tissue cells that we were deal ing with, the explanation would be at once accepted, according to the well-known correlation between fat, myxomatous tissue, and cartilage. The facts seem to require that the same formative possibilities be granted to epithelial cells ; so that the myxomatous and cartilaginous formations in secreting structures would be traced to their active elements. The supporting tissue of the glands is a priori passive, and, as a matter of fact, it has not been proved by any detailed observations to be the source of those myxomatous and cartilaginous new formations. The occurrence of vesiculated epithelial cells with firm hyaline contents is not the only piece of positive evidence. It is much more common to find the columnar epithelial cells elongating into fibre -like elements, straight or crescentic, and developing mucous or hyaline intervals of inter cellular substance ; in this way there results the myxomatous and fibro- cartilaginous tissue that is so often found in the tumour- disordei s of the salivary glands and more rarely in the labial mucous glands. The glandular plan of the structure in these cases very soon becomes obliterated, and the limits between supporting tissue and secreting apparatus removed ; in a considerable area of hyaline cartilage or nbro-cartilage there are naturally few or no traces left of the apparatus and process of secretion ; and there may some-
