We pass on to green old age and decrepit old age, and in these periods the diseases are chronic.

There are diseases that especially belong to this time of life, such as cancer, a disease for which no prevention and no remedy has yet been discovered. Grout, too, belongs more particularly to this time of life.

In old age, however, the first great thing is to avoid the cold. Cold which is so destructive to young children is destructive also to old people, and the old proverb, "A green winter a full churchyard," is like a good many other old proverbs, a total mistake. It is during cold winters that the highest death rates are observed, and this is because so many old people die from cold.

Old people cannot stand the cold, and they require to be warmly clad, and not to be exposed too much to the cold air in winter. But the reason that old people cannot stand the cold is because they cannot manufacture sufficient heat to resist it, the actions of the various organs are going on slower, respiration goes on slower, the capacity of the lungs is smaller, the elasticity of the air-sacs of the lungs is impaired, so that they do not recoil and drive out the air in the way they did when young. The respiration is enfeebled, the beats of the heart are slower, the arteries do not recoil as well upon the blood, that is, they do not force it along as well, and so there is a weakened respiration, and weakened circulation, less oxygen taken into the blood, slower circulation of the blood, less oxidisation going on in the blood, and less animal heat produced; and so old persons do not produce sufficient animal heat to allow them to expose themselves to the cold in the way they were able to do when they were younger, and that is why so many deaths in old age are caused by the cold ; the circulation of blood in thè skin is impeded, and the blood is thrown upon the internal organs, some of which, being perhaps already diseased, fall readily into a state of severe disease, which ends in death through lung disease, kidney disease, and so on. The action of the skin tends to become extremely languid, and as cold cannot be borne by old people, they should stimulate the action of the skin by frequent washing with tepid water.

I may here mention that during the earlier periods of life washing with cold water is an exceedingly important thing, and it should be performed early in the morning, not merely from the point of view of cleanliness, but from the general tonic effect on the system, and people who cannot stand cold water all through the year should use the water slightly tepid. If young people do not have a proper reaction after a cold sponging in the winter, they ought not to take the chill off the water, as they are generally told to do ; that makes it a warm bath, and is a mistake ; but they should add just sufficient warm water to it as to make it only a little colder than themselves, so that it may have the tonic effect, and it will then have the same effect as when they take their cold bath in summer.

Perhaps the most important thing to attend to in old age, after the avoidance of exposure to the cold, is the action of the skin, and another thing is that the food should be divided very carefully. The division of the food is an important thing during the whole of life. A great deal depends upon our masticating our food. Most of us eat our food much too fast, giving our stomachs a great deal to do which our teeth ought to do. This is a great mistake, and one of the most common causes of indigestion.

In extreme old age, of course, cold would be a very pernicious thing, but by the time an old man has got to Shakspeare's " sans teeth, sans eyes, sans taste, sans everything," he has learned wisdom, and he does not expose himself to the cold weather, and so, as a matter of fact, the cold is not the main agent of death among decrepit old people, because they do not expose themselves to it; they die because the end of their work has come, because their system has gone on working as long as it is able to work; the lungs stop working, the blood ceases to be aerated, the heart stops beating, and life is over.

There are certain precautions which should be taken while people are recovering from severe illnesses-during their convalescence.

The first sign of convalescence, or of the recovery of health after severe acute disease, such as a severe fever, is the return of hunger. During the course of the disease the patient has evinced no hunger, and you have been doing everything you could devise to induce him to take what nourishing food he was capable of digesting, although he cared nothing about it. In many diseases recovery depends upon feeding the patient The first sign of his getting well is hunger, and there axe two things which have to be guarded against The first is over-feeding.

The system is very weak, the stomach has been for a long time.supplied with bad blood, and it is not in a condition to stand a heavy meal, and so convalescents should be fed sparingly, and with only the most digestible things. When the sign of hunger returns, they should be fed at first with milk or broths, beef-tea, and jellies, and extremely digestible things of that kind. After that they should be fed with fish, boiled fowl, and so on, until a regular mixed diet is reached. Another warning is that you should not be deceived by false signs of hunger. The true sign of the return of real hunger is the return of taste, properly so called. If a person is getting well from a severe fever, and evinces a desire to eat chalk, or sponge, or slate-pencils, or strange articles of that sort, that is a false taste, not a sign of true appetite; you ought to be more on your guard than ever about feeding him. The first sign, then, of convalescence, is the return of hunger, with a taste for proper kinds of food.

The nervous system is in a very excitable condition, because it has been long supplied with bad blood- perhaps with poisoned blood-and persons recovering from severe diseases should not be exposed to much noise by people talking to them, or else they will get headaches, noises in the ears, dizziness, and signs of that kind. Lying a veiy long time in bed, perhaps perspiring a good deal, the skin is rendered very sensitive to cold, and it is extremely important that people who are in this condition should he prevented from catching cold. It is important, in all cases, but especially important during convalescence from certain diseases. One of these is scarlet fever, after which they are liable to catch cold which settles on their kidneys and produces kidney disease; this very commonly follows scarlet fever. Catching cold is a very dangerous thing after measles and whooping-cough. Children do not die from measles and whooping-cough themselves, but they often die from the lung diseases that they catch by taking cold while they are getting well.

As regards rheumatic fever, if you catch cold you are very liable to get it again, and every time you get it it is more and more likely that you will get heart disease. After rheumatic fever there is, then, a special reason for preventing people from catching cold.

There is a particular danger that arises while people are getting well from typhoid or enteric fever. In typhoid fever those glands in the small intestines, which we call " Peyei^s patches," are ulcerated. Ulcers form in the small intestines during typhoid fever. Now, it frequently happens, that while people are getting well from typhoid fever, if they get up too soon and go about, or sit up in bed, one of these ulcers will break through the wall of the intestines and let the contents out into the cavity of the peritoneum, causing inflammation, extreme pain, and death; so that, in typhoid fever, you should be extremely careful, even in the mildest cases, that convalescents do not move about too soon, because, while they are getting well from typhoid fever, these ulcers still exist; if the person remains quiet they will most likely heal up, and he will get well. I have known it occur that a person has sat up in bed, broken one of these ulcers, and fallen back dead. Exercise should be taken very gradually by persons recovering from these diseases, for very obvious reasons, because they are very weak. They should first walk about their rooms; then about in the house ; and then out of doors in the freshest part of the day, when it is neither too hot nor too cold, and, of course, in fine weather.

The beds upon which sick people lie should be neither too hard nor too soft, except in the case of rheumatic fever, when it is difficult for them to be too soft. Their covering should not be too heavy, and one precaution, especially, should be taken-that is, that people suffering from rheumatic fever should not sleep in sheets, but in flannels and blankets, not in linen or cotton of any kind; and the reason is, that they perspire so copiously, that the sheets become wringing wet, and are of necessity left so, because to move persons suffering from this disease is so painful.

One of our first authors on heart disease says that he believes two-thirds of the cases of heart disease after rheumatic fever might be prevented by this simple precaution.

Ventilation of the sick room is a very important thing. Fresh air should always be admitted into these rooms, and the best way to admit it, especially if the person is suffering from an infectious disease, is to open the windows on the staircase of the house, so as to let the air from the house into the sick room. If you open the windows in the sick room, the air from the sick room gets blown into the rest of the house; so it is necessary to have fresh air in the sick room, and, at the same time, to take precautions that that fresh air shall not pass through the sick room and carry the poison of the disease into the rest of the house.