disposed at hours of meat, and of sleep, and of exercise, is one of the best precepts of long lasting.

"As for the passions and studies of the mind, avoid envy, anxious fears, anger fretting inwards, subtle and knotty inquisitions, joys and exhilarations in excess, sadness not communicated. Entertain hopes,—mirth rather than joy, variety of delights rather than surfeit of them; wonder and admiration, and therefore novelties; studies that fill the mind with splendid and illustrious objects, as histories, fables, and contemplations of nature.

"If you fly physic in health altogether, it will be too strange for your body when you shall need it; if you make it too familiar, it will work no extraordinary effect when sickness cometh. I commend rather some diet for certain seasons, than frequent use of physic, except it be grown into a custom; for those diets alter the body more and trouble it less.

"DESPISE NO NEW ACCIDENT IN YOUR BODY, BUT ASK OPINION OF IT. In sickness, respect health principally; and in health, action; for those that put their bodies to endure in health, may in most sicknesses which are not very sharp, be cured only with diet and tendering. Celsus could never have spoken it as a physician, had he not been a wise man withal, when he giveth it for one of the great precepts of health and lasting, that a man do vary and interchange contraries; but with an inclination to the more benign extreme: use fasting and full eating, but rather full eating;

K

watching and sleep, but rather sleep; sitting and exercise, but rather exercise, and the like; so shall nature be cherished, and yet taught masteries."*

* Bacon's Essays On Regimen of Health.

131

PART II.

SYMPTOMS, CAUSES, THERAPEUTICS AND CURE

OF CONSUMPTION.

CHAPTER I.

SEMEIOLOGY.

"The separation of the dissimilar,-of the general from the special, is not merely useful in facilitating the acquisition of knowledge; it further gives an elevated and earnest character to the study of Natural Science. As from a higher station we survey larger masses at once, so are we pleased to grasp, mentally, what threatens to escape the powers of our senses."-HUMBOLDT.

THE CHEST is divided vertically from front to back into two compartments, by a membranous partition or fold of the pleura. On one side of this partition is placed the right lung divided into three lobes; on the other is the left, divided only into two, the place of the third being, as it were, occupied by the heart, which

lies on this side of the chest.

Into the lungs the air penetrates through the windpipe, a round tube, which may easily be felt running down the front part of the neck, and kept open by a series of cartilaginous rings passing nearly all round it for that purpose. At the bottom of the neck, opposite the narrow space between the collar bones, the windpipe divides into two principal branches, a right and a left, and these again subdivide, the right into three, and the left into two lesser branches, corresponding with the number of lobes in the lung they severally supply. In the interior of the lung, the air-tubes further divide and subdivide, until at length entering the lobules, and attaining a great degree of minuteness, they finally terminate in closed extremities-the air-spaces.

A pulmonary lobule, though it be no larger than a pea, is a perfect respiratory organ by itself, the whole lung being but a series of reduplications of the same structure-an aggregate of lobules. The form of the lobules-like that of the air-spaces-is determined by mutual pressure against each other; it is, therefore, irregular. At one of the corners or angles of a lobule, a division of the pulmonary artery, and a branch of the air-tube enter into its interior, at the same place a vein comes out; and it is principally by these three tubular structures that each lobule is connected with the rest. The practical point to be here noticed, and which will complete our account of the morbid anatomy of consumption, is that respecting the relation of

the walls of air-spaces, to air-tubes on the one hand,— and to blood-vessels-arteries and veins-on the other.

All the branches of the air-tube, and all the ramifications of the vascular system, before entering the interior of lobules, pass in the interstices between them; and here,-embedded in a loose areolar texture, arteries, veins, and air-tubes, have severally their own distinctive structure. But after sundry subdivisions within the lobules, they at length incorporate with the parenchymatous texture; and so completely are they blended in the walls of the air-spaces, that it is impossible, though we use the highest microscopical powers, to discriminate the elements continuous with the coats of arteries and veins, from those continuous with airtubes-that is to say, the outer surface of the transparent membrane, circumscribing an air-space,—where it comes in contact with the surface of the next adjoining, contributes its moiety to form the walls of the capillaries; and is therefore continuous with the interior of arteries and veins; whilst its inner surfaceagainst which the air impinges-is continuous with the interior of air-tubes. But the interior of all bloodvessels is a serous texture; and the interior of air-tubes a mucous texture; it is therefore the more particularly to be remarked, in the walls of the air-spaces, that the distinction blends and disappears, being no longer recognizable; the texture, however, is so thin and simple, that it has more the character of a serous than a mucous structure.