but in the majority of dissections, the whole of the glands that contain true gastric cells are in the shape of simple tubes.

The tubes vary in length and width in different parts of the organ. Thus, taking a considerable number of measurements at random from my notebook, I find that, on the average, they were an inch in length in the splenic,

of

of an inch in

the middle, and of an inch in the pyloric region. In each case the length was reckoned from the lower termination of the tube to the free surface of the mucous membrane. In width, the average diameter was of an inch in the splenic, of an inch in the middle, and of an inch in the pyloric region.

In many of the lower animals, and in the child in the human subject, the tubes are grouped together into bundles of threes to five or six; each group being separated from those adjoining it by partitions of fibrous tissue, muscular fibres, and blood-vessels. In the human adult, this arrangement is seldom to be perceived, but, at pretty regular intervals, we may observe divisions formed of firmer bundles of fibres and larger branches of blood-vessels than are met with between each individual tube.

These bundles of connective tissue are continuous below with the loose layer of fibres on which the tubes rest, and above they are attached to the edges of the projecting ridges that surround the pits on the surface of the stomach. Similar, but weaker processes, are sent up in like manner around each separate tube, so as to support it in its position. It results from this arrangement, that the gastric tubes are, in a healthy state, only firmly fixed at their attachments to the

THE TUBES OF THE STOMACH.

11

pits into which they open; we can therefore teaze them out with needles, or in a section separate them one from the other by compression. In the pyloric region, the connective tissue is much stronger than in the other parts of the organ, and the tubes are consequently much more firmly fixed. One of the most evident effects of inflammation, when it attacks the connective tissue below and between the tubes, is to fasten them together, so that it is difficult or impossible to separate them without injuring their basement membrane. (See plate 5, fig. 1.)

The walls of the tubes are formed of a thin structureless membrane named the basement membrane. This is a continuation of a similar tissue, which constitutes the basis of the surface of the mucous membrane and of the pits into which the tubes enter. We We may, therefore, look upon the tubes as merely reduplications of the inner surface of the stomach, surrounded by connective tissue and blood-vessels.

The tubes are filled with cells by which the characteristic secretion of the organ is elaborated. (See g, plate 2, fig. 1.) In the normal condition, the gastric tubes appear to have no cavity, although, in certain cases, I have seen the epithelium lining their sides separated by a considerable interval, the space between them being filled with the products of inflammation.

As it has been stated by some. authors that the free ends of the tubes present a distinct opening, I attempted to determine the point by the following experiment. A small quantity of collodion was poured into a strong, wide-mouthed glass bottle, which was closed by a piece of healthy human stomach being firmly tied around its neck; the mucous mem

brane being placed inwardly. The bottle was then placed in an inverted position for a short time in hot water, and the expansion of the ether forced the collodion into all the crevices in the surface of the mucous membrane with which it was in contact. When the stomach was removed, the collodion on drying left a film which could be readily torn off with forceps. Under the microscope this film presented a perfect cast of all the various inequalities of the mucous membrane, but I could not discover any openings in the tubes, excepting when the organ was diseased.

In the splenic and middle regions of the human stomach, the tubes contain only what are termed gastric cells; but, in the pyloric region, they are often lined throughout with the ordinary columnar cells which cover the surface and the pits of the mucous membrane. In cases of disease I have seen projections of the basement membrane passing between the gastric cells, and in some of the lower animals this arrangement may be generally observed.

The gastric cells are, when mature, oval or irregular in shape, and usually vary from 26 to 10 part of an inch in diameter. In cases of disease, they are often only 22, and, in other preparations, I have found them as large as or part of an inch.

The cells are much less clearly defined at the bulbous terminations than towards the free ends of the tubes. They contain a well-defined nucleus, a number of granules, and usually fat globules. I have generally found in the lower animals the cells most distinctly fatty when death occurred whilst digestion was in progress. This fact should be borne in mind before we pronounce that fatty degeneration is present

THE SOLITARY GLANDS OF THE STOMACH.

13

in any specimen of gastric mucous membrane we may be examining.

Besides the tubular glands, we sometimes find in the mucous membrane of the human stomach a number of closed follicles similar in structure to the solitary glands of the intestines. These were first clearly described by Dr. Handfield Jones, and may be seen in the stomachs of many animals, as, for instance, in that of the pig, when the mucous membrane has been immersed in dilute hydrochloric acid. (See plate 8, fig. 1.)

In the human subject they are most frequently found in children, in whom the whole surface of the lining membrane of the stomach often seems studded with them. In the adult we frequently fail to discover any trace of them, but in those who have died from certain forms of cancer they appear everywhere disseminated over the mucous membrane. They are most common in the pyloric region and along the curvatures, especially in the smaller.

When examined microscopically, the solitary glands of the stomach seem to consist of an envelope of fibrous tissue, and are filled with nuclei and small cells. Sometimes no distinct limitary membrane can be seen, and they appear simply as a mass of cells and nuclei, of a round or oval form, situated below the secreting tubes. I have never been able to discover any outlet to them; but when injecting portions of the mucous membrane with collodion, I have found casts of small round sacs which communicated with the surface by very narrow openings.

The mucous membrane of the stomach is plentifully supplied with blood. The smaller arteries divide in the submucous tissue, and from these branches pass up

between the tubes, terminating in a beautiful network of capillaries around the openings of the pits situated on the surface. From this network arise the veins, which descend along the tubes, and pour their contents into the larger vessels situated below the mucous membrane. (See plate 5, figs. 2 and 3.)

The minute branches of the nerves have not been traced into the substance of the mucous membrane itself, although they no doubt pass upwards with the blood-vessels between the secreting tubes.

The stomach is surrounded with muscular fibres arranged in three separate layers. The most external are longitudinal, and are continuous with those passing downwards from the oesophagus. They are chiefly spread over the curvatures. The circular fibres envelope the whole of the stomach, and are thickest at the pylorus, where, with the mucous membrane covering them, they form the pyloric valve. The oblique muscular fibres pass obliquely round the organ, and are chiefly found at the splenic end, descending on its anterior and posterior surfaces.

The peritoneal is connected with the muscular coat by means of areolar tissue, and presents, when examined with the microscope, the same structure as membranes of a similar kind situated in other parts of the body.

The inner surface of the small intestines has numerous folds, by which the extent of the mucous membrane is greatly increased. These commence one or two inches below the pylorus, and are most fully developed in the lower part of the duodenum and the upper part of the jejunum.

The mucous membrane of the duodenum is not so