§15Διὰ τί δὲ τὰ ἔχοντα δέχεται τὸν ἀέρα καὶ ἀναπνέουσι, καὶ μάλιστ’ αὐτῶν ὅσα ἔχουσιν ἔναιμον, αἴτιον τοῦ μὲν ἀναπνεῖν ὁ πνεύμων σομφὸς ὢν καὶ συρίγγων πλήρης.
As to why those that have a lung receive the air and breathe, and especially of them, those which have it blood-rich, the cause of breathing is the lung, being spongy and full of tubes.
Καὶ ἐναιμότατον δὴ μάλιστα τοῦτο τὸ μόριον τῶν καλουμένων σπλάγχνων.
And indeed, this part is the most blood-rich of those called the viscera.
Ὅσα δὴ ἔχει ἔναιμον αὐτό, ταχείας μὲν δεῖται τῆς καταψύξεως διὰ τὸ μικρὰν εἶναι τὴν ῥοπὴν τοῦ ψυχικοῦ πυρός, εἴσω δ’ εἰσιέναι διὰ παντὸς διὰ τὸ πλῆθος τοῦ αἵματος καὶ τῆς θερμότητος.
Whichever animals indeed have it blood-rich require rapid cooling because the momentum of the psychic fire is small, and also require the cooling to penetrate entirely inward because of the abundance of blood and heat.
Ταῦτα δ’ ἀμφότερα ὁ μὲν ἀὴρ δύναται ῥᾳδίως ποιεῖν· διὰ γὰρ τὸ λεπτὴν ἔχειν τὴν φύσιν διὰ παντός τε καὶ ταχέως διαδυόμενος διαψύχει· τὸ δ’ ὕδωρ τοὐναντίον.
And both of these the air is able to do easily; for because of having a subtle nature, and permeating everywhere and quickly, it cools; but water is the opposite.
Καὶ διότι δὴ μάλιστ’ ἀναπνέουσι τὰ ἔχοντα τὸν πνεύμονα ἔναιμον, ἐκ τούτων δῆλον· τό τε γὰρ θερμότερον πλείονος δεῖται τῆς καταψύξεως, ἅμα δὲ καὶ πρὸς τὴν ἀρχὴν τῆς θερμότητος τῆς ἐν τῇ καρδίᾳ πορεύεται τὸ πνεῦμα ῥᾳδίως. §16Ὃν δὲ τρόπον ἡ καρδία τὴν σύντρησιν ἔχει πρὸς τὸν πλεύμονα, δεῖ θεωρεῖν ἔκ τε τῶν ἀνατεμνομένων καὶ τῶν ἱστοριῶν τῶν περὶ τὰ ζῷα γεγραμμένων.
And why indeed those that have a blood-rich lung breathe most of all is clear from these; for that which is hotter requires more cooling, and at the same time the breath also travels easily towards the source of heat in the heart. In what manner the heart has its connection with the lung must be observed both from dissections and from the 'Histories of Animals' written about them.
Καταψύξεως μὲν οὖν ὅλως ἡ τῶν ζῴων δεῖται φύσις διὰ τὴν ἐν τῇ καρδίᾳ τῆς ψυχῆς ἐμπύρωσιν.
In general, then, the nature of animals requires cooling because of the ignition of the soul in the heart.
Ταύτην δὲ ποιεῖται διὰ τῆς ἀναπνοῆς, ὅσα μὴ μόνον ἔχουσι καρδίαν ἀλλὰ καὶ πνεύμονα τῶν ζῴων.
And those of the animals that have not only a heart but also a lung effect this cooling through breathing.
Τὰ δὲ καρδίαν μὲν ἔχοντα, πνεύμονα δὲ μή, καθάπερ οἱ ἰχθύες διὰ τὸ ἔνυδρον αὐτῶν τὴν φύσιν εἶναι, τῷ ὕδατι ποιοῦνται τὴν κατάψυξιν διὰ τῶν βραγχίων.
But those that have a heart indeed, but not a lung, like fish, because of their nature being aquatic, effect their cooling with water through the gills.
Ὡς δ’ ἡ θέσις ἔχει τῆς καρδίας πρὸς τὰ βράγχια, πρὸς μὲν τὴν ὄψιν ἐκ τῶν ἀνατομῶν δεῖ θεωρεῖν, πρὸς δ’ ἀκρίβειαν ἐκ τῶν ἱστοριῶν· ὡς δ’ ἐν κεφαλαίοις εἰπεῖν καὶ νῦν, ἔχει τόνδε τὸν τρόπον.
But how the position of the heart is in relation to the gills, for visual inspection one must observe from dissections, and for accuracy from the 'Histories'; but to speak in summary even now, it is in this manner.
Δόξειε μὲν γὰρ ἂν οὐχ ὡσαύτως ἔχειν τὴν θέσιν ἡ καρδία τοῖς τε πεζοῖς τῶν ζῴων καὶ τοῖς ἰχθύσιν, ἔχει δ’ ὡσαύτως.
For it might seem that the heart does not have its position in the same way in land animals and in fish, but it does have it in the same way.
Ἧι γὰρ νεύουσι τὰς κεφαλάς, ἐνταῦθ’ ἡ καρδία τὸ ὀξὺ ἔχει.
For in the direction in which they incline their heads, in that direction the heart has its apex.
Ἐπεὶ δὲ οὐχ ὡσαύτως αἱ κεφαλαὶ νεύουσι τοῖς τε πεζοῖς τῶν ζῴων καὶ τοῖς ἰχθύσι, πρὸς τὸ στόμα ἡ καρδία τὸ ὀξὺ ἔχει.
And since heads do not incline in the same way in land animals and in fish, the heart has its apex towards the mouth.
Τείνει δ’ ἐξ ἄκρου τῆς καρδίας αὐλὸς φλεβονευρώδης εἰς τὸ μέσον, ᾗ συνάπτουσιν ἀλλήλοις πάντα τὰ βράγχια.
And there extends from the apex of the heart a vein-and-sinew-like tube into the middle, where all the gills connect with one another.
Μέγιστος μὲν οὖν οὗτός ἐστιν, ἔνθεν δὲ καὶ ἔνθεν τῆς καρδίας καὶ ἕτεροι τείνουσιν εἰς ἄκρον ἑκάστου τῶν βραγχίων, δι’ ὧν ἡ κατάψυξις γίνεται πρὸς τὴν καρδίαν, διαυλωνίζοντος ἀεὶ τοῦ ὕδατος διὰ τῶν βραγχίων.
This, then, is the largest, and on this side and that of the heart others also extend to the extremity of each of the gills, through which cooling is effected towards the heart, as the water is constantly channeled through the gills.
Ὡσαύτως δὲ τοῖς ἀναπνέουσιν ὁ θώραξ ἄνω καὶ κάτω κινεῖται πολλάκις δεχομένων τὸ πνεῦμα καὶ ἐξιέντων, ὡς τὰ βράγχια τοῖς ἰχθύσιν.
In the same way as with those that breathe, whose chest moves up and down as they repeatedly receive and emit the breath, so do the gills for fish.
Καὶ τὰ μὲν ἀναπνέοντα ἐν ὀλίγῳ ἀέρι καὶ τῷ αὐτῷ ἀποπνίγονται· ταχέως γὰρ ἑκάτερον αὐτῶν γίνεται θερμόν· θερμαίνει γὰρ ἡ τοῦ αἵματος θίξις ἑκάτερον.
And breathing animals are suffocated in a small quantity of air, and in the same air; for quickly each of them becomes hot; for the contact with the blood heats each.
θερμὸν δ’ ὂν τὸ αἷμα κωλύει τὴν κατάψυξιν· καὶ μὴ δυναμένων κινεῖν τῶν μὲν ἀναπνεόντων τὸν πνεύμονα τῶν δ’ ἐνύδρων τὰ βράγχια διὰ πάθος ἢ διὰ γῆρας, τότε συμβαίνειν τὴν τελευτήν.
And the blood, being hot, prevents cooling; and when the breathing animals are unable to move the lung, and the aquatic animals their gills, because of disease or old age, then death occurs.