Among _irritants_ taken as food, may be named hot mashes, bolted by a hungry and gluttonous horse, and temporarily arrested in the gullet by reason of the resulting irritation of the mucous membrane. In other cases, coarse fibrous fodder is bolted without previous mastication, and scratches and abrades the œsophagean mucosa leading to transient or progressive inflammation. In other instances diseases of the teeth, jaws, temporo-maxillary joint, or salivary glands prevent the necessary trituration of the food, and it is swallowed in a rough, fibrous, or even a dry condition. Again the impaction of a solid body (turnip, apple, potatoe, egg) or of a quantity of finely divided grain or fodder so as to obstruct the lumen of the gullet, is an occasional cause. The density of the epithelium reduces these dangers to the minimum, yet a too rough morsel, or an undue detention of the less irritating material will determine hyperæmia and even inflammation and infective invasion. Acrid and irritant vegetables in the food are less injurious when thoroughly insalivated, as their contact with the œsophagean walls is then very slight and transient. _Irritant and caustic chemical agents_ given for therapeutic purposes, attack the mouth, pharynx and stomach, more severely than the gullet through which they are passed with great rapidity. In some cases, however, the agent will adhere by reason of its powdery, gummy or balsamic character and will then act as a direct irritant. Solutions of caustic alkalies (weak lye) given to correct acid gastric indigestion in the horse, and ammonia to remedy tympany in cattle, when insufficiently diluted, will dangerously attack the œsophagean mucosa. _Parasitic irritation_ is not so common here as in other parts of the intestinal canal where the contents are longer delayed and are passed with less friction, yet certain parasites are found in this region and may even produce considerable irritation. The gongylonema of the thoracic œsophagean mucosa of ruminants and swine are apparently harmless. The psorospermia of the œsophagean muscles of the same animals are alleged to cause œdema of the glottis, asphyxia and epilepsy. The spiroptera microstoma of the horse has in one instance known to us caused extensive denudation of the muscular coat within a foot of the cardiac end of the gullet. Finally we have found bots hooked on to the œsophagean mucosa close to the cardia, causing much irritation and spasm. The spiroptera sanguinolenta is often present in chambers hollowed in the œsophagean mucosa of the dog.