The History of a Mouthful of Bread / And its effect on the organization of men and animals

by Jean Macé

The two great compartments are called ventricles, the two small pouches auricles, and they are also distinguished as being on the right or left side;—right ventricle, left ventricle, right auricle, left auricle.

The inner doors on which depends all the action of the machine, are called valvelets. By-and-bye, when the pump and the steam-engine are explained to you, you will meet again with these treacherous doors, which never allow what has once entered to go back again; but then we shall call them valves.

The air-reservoir, I need scarcely tell you, is the lung, to which the blood goes to put itself in contact with the air.

The subterranean watercourse, of which I hope we have talked long enough, is the small intestine, in which the chyle collects; and the tubes which run into it are, of course, the chyliferous vessels, the only channels by which anything reaches the heart which has not previously gone out from it.

The tubes of distribution, which run out from the machine in all directions, are called with us arteries; the return tubes, which bring back the water to the machine, are called veins.

Finally, we have not exactly the filters employed to clear the water from the impurities contracted as it goes along, for no such thing exists in us. There are in our case the refuse-chambers of which I have already spoken, in connexion with the liver, where the blood disembarrasses itself of any useless materials, and from which it comes out with clean pockets, so to speak, reverting to the comparison of which we have already availed ourselves.

As you see, then, everything comes round again; and the bright idea which our professors hit upon in order to satisfy the caprice of the banker is exactly carried out in your own body, only a thousand times more perfectly than could have been done by them all, even with all their science added to all his money.

I mentioned that the shrewdest of the party boasted about making an artificial heart. But, let me tell you, there is one thing I would have defied him to imitate, by any expedient he could devise, and that is the inimitable construction of the arteries and veins, and the incomprehensible delicacy of their innumerable ramifications.

Let us talk a little about these marvellous tubes, and begin with the arteries, which have the most important part to play.

Did you ever see a doctor try the pulse of his patient? Take hold of your own wrist and search a little above the thumb. You will soon find the place and feel something beating against your finger. There is an artery which passes there, and the little beating you feel is the rebound of the pulsations, of your heart. Every time that the left ventricle, by contracting itself, chases the blood into the arteries, these, of which the tissue is very elastic, become distended all at once, and then contract again, repeating the process whenever a fresh gush of blood arrives, so that their movement is exactly regulated by the movement of the heart. It is true the two movements are in a contrary direction; that is to say, the artery becomes distended, while the heart contracts, and contracts when the heart enlarges itself; but that makes no difference to the doctor. What he wants to know is, with what force and rapidity the heart of the patient beats, and I will explain why. It is an interesting point in the history of circulation.