The lesions are seated in the superficial epithelium, the gland cells, the interstitial tissue, the follicular apparatus, and the vessels, in every possible combination of involvement. The superficialepithe lium covers the inner surfaee of the stomaeh and entire intestinal tract without a break, as I have demonstrated and Reyher has confirmed, in contradiction to the observation of Disse. On this superficial epi thelium occur necroses as a result of capillary hatmorrhages (Bloch) which create small areas of loss of substance. These lesions can attain important significance on account of their naultiple and widespread occurrence as well as through the destruction of the normal defence against the bacteria always numerous in the mucous coating covering the mucosa (Alarfan and Bernard) and also through the alternating of absorption conditions (Fig. m on Plate 48 and Fig. II, Plate 46). The coating over of the epithelium with mucus is regarded by Heubner as the expression of a process of defence against toxic irritation of the inner bowel surface, while Tugendreich disputes its pathogenic impor tance, and, on a basis of researches on the intestines of young (logs, regards it as a normal appearance connected with the physiologic pro cess of digestion. It is a universally establishecl fact, that the severest diseases of nutrition of long duration leading to atrophy do not neces sarily affect the superficial epithelium at all, so that in fresh specimens it presents a normal appearance in all the parts examined. On the other hand there are processes of acute and chronic course, which leave. behind their traces in this tissue-layer, and lead to destruction o'r Et peculiar swelling of the epithelium, obliteration of the cell walls, and destruction or difficult staining of the nuclei. In these cases the micro scopic picture suggests the action of a severe poison, and finds an anal ogy in the lesions of experimental poisoning. On the basis of my own researches with material carefully obtained, preserved, and treated, I must mention a destruction of the superficial epithelium occurring over wide areas, with subepithelial Inemorrhage, necrosis of the deeper tissue, and fibrin formation in and around the area of loss of substance. Examples of this are to be found among the microscopic pictures (Fig. h on Plate 47).
I have observed a peculiar form of swelling in the gland cells of the stomach, which I consider a coagulation necrosis. 'f his is also shown in the illustrations. Marfan and Bernard describe similar changes in the gland cells of the stomach and intestine as a mucoid degenera tion, and demonstrate their mucous character by appropriate staining methods. There is also a preparation exemplifying this (Fig. I, Plate 46).
Only further investigation with different methods of preservation will show to what extent vacuole-formation in the intestinal epithelium represents au artificial finding, because in alcohol preparations the fat drops are dissolved and leave in their place vacant spaces.
To sum up, there can be no doubt aeeording to the present stage of our knowledge, that, especially in the course of acute diseases of nutrition, there can be observed a number of significant lesions in the superficial ancl glandular epithelium which have certainly developed during life, and which can not be without importance for the function of the mucous membrane.
Baginsky has described hypertrophic processes in the crypts of Lieberkiihn, through which the crypts on the one hand grow up above the level of the mueous membrane, and on the other hand break through Briicke's muscle (museularis mucosa) and sink into the submucosa. Cysts result from this, through coalescence of several dilated tubules. Held-mei. considers 61101 a picture due to oblique sections. Tugendreich, who recognizes the eyst-formation, finds the downward growth of the glands into the sulimucosa only in places where there are follicles, as there the Brficke's muscle is deficient, and the glands can easily pen etrate into the soft follicular tissue. I freely admit this latter possi bility, but. my own preparations, one of which is reproduced here (Fig. d on Plate 47) lead me to consider Baginsky's observation entirely correct. Also cysts can be found without this hypertrophic process, as is shown in one of the preparations reproduced here, in which cysts appear in the midst of the. regular parenchyma of the crypt, and are to be explained by retention of secretion. In some places are seen swollen gland cells which appear partly necrotic, near which are clumps of microscopic networks of fibrin, and masses of mucus. In other places the swollen cells have entirely disappeared, leaving only homog eneous lumps, while a flattened cylindrical epithelium lines the cyst. In the neighboring cysts are seen similar lesions in the cells, a deep extension of the mucous plug down to the bottom of the gland, and bands of mucus, which last also invade the free surface of the mucous membrane.
The vessels present in the more aeute cases the picture of very marked byperfernia, both in the mucosa and submucosa. One fre. quently sees diapedesis of red corpuscles into the tissue, formation of larger htemorrhagic areas, and consequent destruction of specific tissue elements. The more chronic the course of thc disease, the less marked becomes the layperremia, to be replaced by thickening of the arterial walls, and accumulation of inflammatory eells about the vessels.
These latter lesions seem to form the starting point of an inter stitial overgrowth, which is not notable in the acute cases, but which in chronic cases forms the leading feature of the picture. It forces apart the crypts, pushes its way through the tissue of the villi, strangu lates the neck of the glands, thus constituting a further cause of cyst formation, notably increases the thickness of the mucosa, and often densely infiltrates the submucous tissue. I believe that we have every reason for assuming that such a very- marked and widespread process in the intestine must have a notable influence upon the process of absorption by the mucous membrane. In cross-sections can be seen the multiform ways in wh:ch the entangled crypts are distorted and compressed (Figs. i and a, Plates 17 and 48).
As to the distribution of the lesions described above, Bloch, who has made a topographic investigation of numerous divisions of the intestine, has stated that apart from the processes localized in the stomach, the lesions reach their maximum in the region of the cecum, and become less and less above and below the point. This agrees with the fact that in this region the intestinal contents remain longest, and thus can exercise most intensely their injurious action.