plaining the mode in which headache is produced by indigestion, and there can be no doubt that both come

into operation.

First, there is an intimate and direct connection by means of nerves between the stomach and the head. When, therefore, the nerves distributed over the internal lining of the stomach are irritated because they are involved in the general irritation of this lining, the morbid effect is transmitted to the head, and there makes itself known as headache. One form of the disorder, that in which headache comes on immediately after food has been taken, can be attributed to no other

source.

Secondly, imperfect digestion tends to make the blood itself impure. Let it be remembered that the sole purpose of digestion is to supply the vital fluid with fresh material for the support of the body. But if the blood be tainted by the absorption of ill-prepared nutriment, the brain, which is of all our organs the most easily affected by the circulation through it of impure blood, will suffer. In this way pain is developed, if not in the brain itself, in the nerves which it sends off, and which are so abundantly distributed in its immediate neighbourhood.

There is perhaps no more certain cause of headache than taking stimulants in excess, especially if different

kinds be indulged in. The well-known headache on the morning following the indiscretion is unquestionably due to impurities which the excreting organs have as yet been unable to separate from the blood.

It may be here remarked that the circulation in the brain of impure blood, from its having been supplied with ill-prepared chyle, in other words, with a solution of badly digested food, offers an easy explanation of other facts. It shows how the mind itself becomes dulled by indigestion—how the memory becomes impaired and the thoughts confused. It explains the groundless apprehensions and suspicions which haunt the morbid imagination of the hypochondriac. This also indicates how in most cases dizziness, dark images before the eyes, and numerous other head affections are produced.

There is a form of headache which seems to depend on indigestion, since it is attended by the same kind of stomach derangement as that described, in which the connection between cause and effect is not always easy to trace. Like the other, too, it is often called bilious headache, because bile makes its appearance, as already explained, in the vomited matters. People otherwise quite healthy are not unfrequently the subjects of it. It is sometimes strangely periodic in its attacks. A person will tell you, "I cannot keep such and such an engagement, because I shall have my headache on that

day," yet the interval between the attacks may vary from one to several weeks. This may happen too when great care is taken in diet as well as in other respects. Yet indications are seldom wanting that the natural functions of digestion are previously disordered. This headache is usually preceded by constipation of the bowels, and a timely purgative will in many instances for the present ward off an attack. It seems, in fact, as if the unaided bodily machine was unable to keep going without derangement beyond a limited time. In most instances it is a very refractory disorder, and many of those who have been subject to it for a long period resign themselves to their fate; they simply seek for some alleviation by remaining in bed in a darkened room on the day during which generally the attack lasts.

Nervous headache is the kind to which persons of the nervous temperament are particularly subject. The outward characteristics of this temperament are not difficult to define. The form may be rounded, but is not muscular, the features are refined and impressionable, the spirits easily elevated and as easily depressed. There is great susceptibility both of body and mind, and yet both may be surprisingly equal to a great emergency. Hence it is that the softer sex is especially liable to nervous headaches, and the peculiar functions of the female organi

zation increase this tendency throughout a great part of life. The consequence of all this is, that women suffer from headache much more frequently than men.

Like sick headache, nervous headache varies in severity. At times the whole mass of the brain seems invaded by throbbing pain, while at others the pain is much less acute and quite local. It more frequently attacks the upper and back parts of the head than sick headache. A great many physical causes will induce it, and few are more likely to do so than bad ventilation. It is this which makes going to a theatre with many persons equivalent to going to get a headache. The contamination of the atmosphere caused by its having been breathed and rebreathed by a large number of people, is partly the cause, and in addition the great number of gaslights unduly consumes the oxygen of the air, while the products of the gaseous combustion are poisonous. This is so sensibly felt by many persons that headache is sure to come on if they remain even for a short time in any gas-lighted room.

Particular states of the atmosphere at large are also very productive of headache. Many are affected when it is damp and foggy, others when it is dry and searching. The east wind is in this way an enemy to some. The climate of certain localities makes a great difference. We have known instances in which the comparatively

bracing air of Brighton could not be endured on account of headache. The more relaxing atmosphere of South Devonshire is equally injurious to others. The electrical state of the air has also a powerful effect. Some persons get headache at the approach of a thunderstorm, which, although they may be in bed at the time, they can foretell by this means alone.

The foregoing may be regarded as causes which in various ways disturb without exhausting the nervous power; but there is another set of potent causes which exhaust as well as disturb it-excitement, even of a pleasurable kind, in very susceptible persons; depression caused by grief, anxiety, or disappointment, night-watching, over-fatigue, long-fasting, and cold feet, are all well-known causes of headache.

As may be supposed, the causes which produce sick or bilious headache may be combined with those of nervous headache. The complication in such cases

renders the disorder more intractable.

Hysteria is the cause of a singular form of headache. Spasmodic pain is first experienced in the abdomen, from which it extends to the throat and head. Sometimes the headache occupies a mere spot in some part of the head, and the pain is then very intense. It was from these circumstances that it was termed clavus, or the nail, by the old writers. By this is