9th. =Nasal Vertigo= has been noted by Cadeac in connection with irritation in the nose and especially by the larva of œstrus ovis (sheep), and the linguatula (dog, horse). In certain of the cases manifested by jerking of the head and diverging to one side, the recovery after section of the pes anserina indicates a nasal origin. 10th. =Vertigo from Narcotics= (alcohol, lolium temulentum, belladonna, solanum, various essential oils, carbon monoxide, etc.), have been already referred to. 11th. There remains to be noted cases in which no narcotic poison, no mechanical disturbance of the circulation, no visual, aural nor nasal trouble, no gastric nor hepatic disorder, and not even a distant nervous lesion can be found; the disease may in such cases be ranked for the present as =essential vertigo=. _Symptoms._ As usually seen in the horse, vertigo often attacks the nervous, irritable animal in which the slightest occasion of irritation or disturbance causes intense suffering and quick response. This is often aggravated by the plethoric condition of the animal, kept on a liberal ration of grain and having little exercise. In some forms of the affection, however, and especially the gastric and hepatic, the subject is dull, carries the head low, and lacks vivacity and energy. In the first form (the most common in the horse) the animal which has been full of life and vigor, slackens his pace and the tension on the reins, or stops suddenly, shakes the head, vertically or horizontally, or jerks it to one side, trembles, staggers, props his legs outward for more stable support, presses against the pole, or the other horse, or a wall, leans on the breeching or hangs on the breast strap, plunges forward, or to one side, or rears up and even falls backward, and comes to the ground. Profuse perspiration ensues, the eyes roll, the face is pinched and drawn, the prostrate animal may struggle in a helpless way, and, if the harness is loosened, he may get up in a few seconds and slowly recover. Often, however, he remains for an hour or more, nervous, sensitive, bedewed with sweat, trembling and with anxious expression. Such are the more common manifestations of what is familiarly known as blind staggers. The symptoms will vary however, with the cause. In =gastric= or =hepatic= cases there may be more particularly dullness and lack of energy, low carriage of the head, unsteadiness of gait, lack of lustre in the eye, pupils dilated, semi-closed eyelids, pendent lips, a tendency to lean on the stall or hang on the harness, and though the animal may stagger and fall, there is not the abrupt transition from life and energy to the active excitement and uncontrollable movements. The same remarks apply in a measure to narcotic vertigo.