Tenderness on pressure is significant either of local inflammation, whose other signs are then to be discerned, or of non-inflammatory hyperæsthesia. The origin of the latter may require careful examination of various organs for its discovery. If pain is relieved by pressure, we may be sure of the absence of severe acute local inflammation. Not infrequently the seat of disease may be at some distance from that of pain, as in the familiar instances of pain at the top of the head in uterine derangement; in the glans penis from calculus in the bladder; in the knee from hip-joint disease; under the shoulder-blade in liver disorder; about the heart or between the shoulders from dyspepsia. Anæsthesia, loss of sensibility, has much value as a symptom in neurotic affections, as paralysis, etc. Its discussion will find place in connection with diseases of the Nervous System in other portions of this work. As an example of the diversified associations of pain, cephalalgia (headache) may be mentioned as having at least the following possible causes: congestion of the brain, neuralgia, rheumatism of the scalp, uterine irritation, disease of the kidneys, early stage of remittent, typhoid, or yellow fever, alcoholic intoxication, chronic disease of the brain. Abdominal pain may, in like manner, be traced, in different cases, to many morbid conditions, such as flatulent colic, lead colic, neuralgia or rheumatism of the bowels, intestinal obstruction, dysentery, passage of a gall-stone or of a nephritic calculus through one or the other duct {166} respectively; cancer, aneurism of the aorta, caries of the spine; in the female, dysmenorrhoea, metralgia or ovaralgia--_i.e._ neuralgia of the uterus or ovaries. Similar diversity in the origins of pain might, but for want of space, be pointed out in morbid states of the contents of the chest and of other parts of the body. Subjective symptoms often affect the special senses. Taste and touch have been already referred to. Of sight we may have photophobia, connected with exaggerated sensibility of the retina or of the brain; muscæ volitantes, specks, rings, or chains of spots from floating semi-opaque particles in the vitreous humor; diplopia, double vision; hemiopia, seeing only half of an object at a time; amblyopia, indistinctness of vision of all objects.