Next to salivary fistula subsequent upon injuries and ulcerative destruction of the tissues, which occurs chiefly at the ductus stenonianus, but which we have also seen in the shape of pancreatic fistula (see p. 39) discharging by a perforating ulcer of the stomach, we find dilatation of the excretory ducts and of the ductuli salivales to be the chief and most frequent affection that has to be noticed under this head.

Dilatation depends mainly upon retention and accumulation of the secretion, and may either affect the entire duct or one portion uniformly, or small detached points, so as to form saccular or varicose dilatations; in the latter case, again, the duct may present single fusiform or vesicular dilatations at intervals, or numerous closely-set expansions, which are partially separated from one another by valvular folds formed by the coats of the duct. The coats may be either considerably thickened or considerably attenuated.

The cause is generally to be found in some mechanical impediment, such as compression and complete obliteration of the duct external or internal to the gland by morbid growths of various descriptions. In the pancreatic duct it may be induced by gall-stones occupying the orifice of the ductus choledochus, by a sudden curve or angle of the duct brought on by cancerous induration and shrivelling of the normal tissue, with change of position, such as we often observe in the pancreatic duct near the head of the pancreas. It may be induced by tumefaction of the internal membrane, by a mucous plug, and especially by calcareous concretions (salivary calculi). In rare cases the dilatation of the pancreatic duct is, like that of the bronchi, brought on by induration and atrophy of the gland. In morbid softening of the gland, and especially in the adipose metamorphosis, the duct is deprived of its contractility, and dilatation with a marked attenuation and relaxation of its parietes ensue; lastly, dilatations of the duct may take place without any mechanical obstruction, in consequence of scirrhoid disease of its duodenal end; the duct in this case fuses with the scirrhous portion of the gland; it is thus fixed, the scirrhus involves its tissue, whereby its vital contractility becomes impaired, and the secretion is allowed to stagnate in its cavity.

The dilatations of the pancreatic duct enlarge to the size of a goose's or swan's quill; the saccular expansions may reach the size of a hazelnut or pigeon's egg. Jn Wharton's duct the dilatation occurs in the shape of a fluctuating tumor, and is known as ranula. Dilatation of the ductuli and their terminations sometimes puts on the shape of serous cysts.

The contents of the salivary ducts, i. e. the saliva of the mouth and stomach, occasionally offer rather remarkable anomalies in reference to quantity, color, consistency, and probably, as indicated by the taste, and especially by its acid or alkaline reaction, in reference to chemical constitution. Not unfrequently calculous concretions, the so-called salivary calculi, are generated in the saliva, and this is more especially the case in the ducts of the sublingual gland and the pancreas. They are white, friable, and either round, oblong, cylindrical, or obovoid; in size varying from that of a millet-seed or a pea, to even that of a hazelnut; they are either solitary, or if small, frequently very numerous (twenty and more); and they are composed of phosphate and carbonate of lime, held together by animal matter. These calculi give rise to obturation of the ducts, and consequent accumulation of the secretion and dilatation.

At times, blood, pus, cancerous sanies, is found in the salivary ducts; bile is not unfrequently discovered in the pancreatic duct; in one case of migration of lumbrici into the biliary vessels, two were found to have crept into the latter.