off from wisdom; though I begin

"To suck the sweets of sweet Philosophy :"

and I mean to persevere, in the hope that I shall find my reward; and in the confidence that

"Truth hath her pleasure grounds"

as well as Romance.

GRACE.

Truth is to me the soul of all things. God himself is Truth and Love!

MRS. F.

Truth is the chief and fundamental part of virtue. We must love it for its own sake. There is a quotation from Dryden, which I found in my commonplace book, which is worthy of a place in yours, Grace:

"The study of truth is perpetually joined with the love of virtue; for there is no virtue that derives not its origin from truth: as, on the contrary, there is no vice which has not its beginning from a lie." The next organ that we shall discuss will be the Lungs : but I have not time to enter upon the subject to-day. We have nearly got through the alarming number of organs, whose names frightened Edith at first.

GRACE.

Yes we have learned something of the Skinthe Muscles and the Bones; and there now only remain the Lungs, and the Nervous System.

EDITH.

I expect the Nervous System will prove most interesting, and you reserve it, as a bonne bouche, for the last, Aunt Ellen.

CONVERSATION IX.

MRS. F.

To-day I am going to tell you something of the Lungs, and of the Circulation of the Blood.

GRACE.

I thought that the heart managed the circulation of the blood, and that the lungs were only occupied with breathing.

MRS. F.

It is true, the lungs are the organ by which we breathe, but they are also necessary to the formation of blood. In the body there are two sorts of blood, differing very much from one another. One is called red, or arterial blood: it is of a beautiful bright ver million colour, full of life and nourishment. This circulates through vessels called arteries; and it is this blood alone that is capable of supporting life: and it owes much of its sustaining properties to the lungs, as I shall presently explain to you. pure blood circulates through every part of the body, and in its course nourishes and feeds the human frame, repairing and sustaining it. In its course it passes through the lungs, where it becomes thus bright and pure. The other kind of blood is a thick, purplish, murky stream, possessing no nourishing qualities this is called dark venous blood, and circulates through vessels called veins. The first kind

H

This

of blood I mentioned, called the red arterial blood, is poured from the left side of the heart, and conducted by a large artery into small arteries, until it is passed through all parts of the body, nourishing every part in its course. Having performed its route, and sustained life, by giving away all its nutritive properties, it becomes dark venous blood, and another set of vessels called veins, like so many waste pipes, takes this deterioriated, dark, altered blood back, and pours it into the right side of the heart.

EDITH.

I see now-veins and arteries are not the same things. I always fancied the large veins were called arteries, and the small ones, veins.

MRS. F.

The arteries are large near the heart, and get smaller and smaller towards the end of their course, where they are mere threads in size; then they meet equally small veins to return the blood: these veins get larger and larger as they approach the heart.

:

GRACE.

I understand the arteries take the pure red blood from the left side of the heart, and distribute it all over the body, whilst the veins take it back, when it has become dark and venous, to the right side of the heart. But what becomes of the venous blood then?

EDITH.

I should fancy it comes out pure and fresh again on the left side?

MRS. F.

Yes: but the assistance of the stomach and lungs is necessary to make it red and pure again. Just before it reaches the heart it mixes with the chyle, which is, as you know, a nourishing substance to which the stomach turns our food; then it is conducted by a large artery, called the pulmonary artery, into the lungs, where it is subjected to the air,

from which it extracts healthful qualities. This is done by the process of respiration, and it is this important office which we are now going to consider. As the food cannot become part of the living animal, or the venous blood regain its sustaining properties till it has undergone a change in the air-cells of the lungs, you may suppose it is very important to health what kind of air we breathe.

GRACE.

The quantity, as well as the quality of the blood, is important, is it not?

MRS. F.

Yes if you tie up your arm tight, and prevent a proper quantity from circulating through it, the limb would shrink up and waste away, from the want of sufficient nourishment; and until a fresh supply of blood is restored, it will not regain its plumpness.

EDITH.

The same thing must happen if the quality is bad, and does not half nourish the limbs.

MRS. F.

Certainly the body languishes when the blood is impaired by too little food or bad digestion, or by the lungs not conveying sufficient air to the blood. This is the case in consumption, when the lungs are too feeble to take in sufficient air to purify the blood. Exposure of the blood to the action of the air seems necessary to every living thing. In man, and the more perfect lower animals, this is carried on by the lungs, which are beautifully fitted for the office by innumerable air cells. In fishes, who do not breathe, the blood circulates through the gills, and thus meets with the air which the water contains. In worms no distinct organ is made for this purpose: they take in air by the surface of their bodies. So very necessary is atmospheric air to the well-being and vitality of the blood, that no animal can live without it.

fish could not live in water deprived of air, any more than a man can live in an atmosphere deprived of oxygen, or pure air.

GRACE.

In respiration the lungs exhale and give out air, as well as take it in.

MRS. F.

The lungs are one of the chief outlets for waste matter from the system.

EDITH.

Like the skin, Aunt Ellen?

MRS. F.

Yes: but they throw out even more waste matter than the skin. In breathing, the lungs only retain the oxygen that is in the air, and give back carbonic acid gas and animal effluvia. Thus, you see, a sufficient quantity of oxygen, or pure air, is necessary to their well-being. Like the skin, too, the lungs absorb thus, if a person breathe the fumes of tobacco, turpentine, or any volatile spirit, it has the same effect on him as if taken into the stomach.

GRACE.

For instance: if animals are made to inhale Prussic Acid, they die in a few minutes, as if they were poisoned.

MRS. F.

Yes. From this power of absorption in the lungs, you see they are an inlet to contagion from miasma, bad air, and other poisonous influences in the atmosphere we breathe.

GRACE.

You said just now, that consumption takes place in consequence of respiration not being perfect enough. to make proper healthy blood in the lungs.

EDITH.

Consumption is a fearful thing; and I should be glad to be well acquainted with the organisation