论呼吸

Thus all things outwards breathe and in;- their flesh has tubes Bloodless, that stretch towards the body's outmost edge, Which, at their mouths, full many frequent channels pierce, Cleaving the extreme nostrils through; thus, while the gore Lies hid, for air is cut a thoroughfare most plain. And thence, whenever shrinks away the tender blood, Enters the blustering wind with swelling billow wild. But when the blood leaps up, backward it breathes. As when With water-clock of polished bronze a maiden sporting, Sets on her comely hand the narrow of the tube And dips it in the frail-formed water's silvery sheen; Not then the flood the vessel enters, but the air, Until she frees the crowded stream. But then indeed Upon the air's escape runs in the water meet. So also when within the vessel's deeps the water Remains, the opening by the hand of flesh being closed, The outer air that entrance craves restrains the flood At the gates of the sounding narrow, upon the surface pressing, Until the maid withdraws her hand. But then in contrariwise Once more the air comes in and water meet flows out. Thus to the to the subtle blood, surging throughout the limbs, Whene'er it shrinks away into the far recesses Admits a stream of air rushing with swelling wave, But, when it backward leaps, in like bulk air flows out. This then is what he says of respiration. But, as we said, all animals that evidently respire do so by means of the windpipe, when they breathe either through the mouth or through the nostrils. Hence, if it is of this kind of respiration that he is talking, we must ask how it tallies with the explanation given. But the facts seem to be quite opposed. The chest is raised in the manner of a forge-bellows when the breath is drawn in-it is quite reasonable that it should be heat which raises up and that the blood should occupy the hot region-but it collapses and sinks down, like the bellows once more, when the breath is let out.…