§10Περὶ μὲν οὖν τῶν ἀναίμων, ὅτι τοῖς μὲν ὁ περιέχων ἀὴρ τοῖς δὲ τὸ ὑγρὸν βοηθεῖ πρὸς τὴν ζωήν, εἴρηται·
Thus, concerning bloodless animals, it has been said that for some the surrounding air and for others the liquid helps toward life.
τοῖς δ’ ἐναίμοις καὶ τοῖς ἔχουσι καρδίαν, ὅσα μὲν ἔχει πλεύμονα, πάντα δέχεται τὸν ἀέρα καὶ τὴν κατάψυξιν ποιεῖται διὰ τοῦ ἀναπνεῖν καὶ ἐκπνεῖν.
But of those that have blood and a heart, as many as have a lung, all receive air and perform cooling through breathing in and breathing out.
Ἔχει δὲ πλεύμονα τά τε ζῳοτοκοῦντα ἐν αὑτοῖς καὶ μὴ θύραζε μόνον (τὰ γὰρ σελάχη ζῳοτοκεῖ μέν, ἀλλ’ οὐκ ἐν αὑτοῖς) καὶ τῶν ᾠοτοκούντων τά τε πτερυγωτά, οἷον ὄρνιθες, καὶ τὰ φολιδωτά, οἷον χελῶναι καὶ σαῦραι καὶ ὄφεις.
And those have a lung that are viviparous within themselves and not only externally (for the cartilaginous fish are indeed viviparous, but not within themselves), and of the oviparous, those with wings, such as birds, and those with horny scales, such as tortoises, lizards, and snakes.
Ἐκεῖνα μὲν οὖν ἔναιμον, τούτων δὲ τὰ πλεῖστα τὸν πλεύμονα ἔχει σομφόν.
Now, the former are full of blood, but most of the latter have a spongy lung.
Διὸ καὶ τῇ ἀναπνοῇ χρῆται μανότερον, ὥσπερ εἴρηται καὶ πρότερον.
Therefore, they also use breathing more sparsely, as has been said before.
Χρῆται δὲ πάντα καὶ ὅσα διατρίβει καὶ ποιεῖται τὸν βίον ἐν τοῖς ὕδασιν, οἷον τὸ τῶν ὕδρων γένος καὶ βατράχων καὶ κροκοδείλων καὶ ἑμύδων καὶ χελῶναι αἵ τε θαλάττιαι καὶ αἱ χερσαῖαι καὶ φῶκαι· ταῦτα γὰρ πάντα καὶ τὰ τοιαῦτα καὶ τίκτει ἐν τῷ ξηρῷ, καὶ καθεύδει ἢ ἐν τῷ ξηρῷ, ἢ ἐν τῷ ὑγρῷ ὑπερέχοντα τὸ στόμα διὰ τὴν ἀναπνοήν.
And all those also use it that spend time and make their living in the waters, such as the race of water-snakes, frogs, crocodiles, pond-turtles, both marine and land tortoises, and seals; for all these and suchlike both bring forth on dry land and sleep either on dry land or in the liquid, keeping their mouth above it for the sake of breathing.
Ὅσα δὲ βράγχια ἔχει, πάντα καταψύχεται δεχόμενα τὸ ὕδωρ· ἔχει δὲ βράγχια τὸ τῶν καλουμένων σελαχῶν γένος καὶ τῶν ἄλλων ἀπόδων.
But as many as have gills are all cooled by receiving water; and the race of the so-called cartilaginous fish and of the other footless animals have gills.
Ἄποδες δ’ οἱ ἰχθύες πάντες· καὶ γὰρ ἃ ἔχει, καθ’ ὁμοιότητα τῶν πτερυγίων ἔχουσιν.
And all fish are footless; for what limbs they have, they have in likeness to fins.
Τῶν δὲ πόδας ἐχόντων ἓν ἔχει βράγχιον μόνον τῶν τεθεωρημένων ὁ καλούμενος κορδύλος.
Of those having feet, the so-called cordylus is the only one among those observed that has gills.
Ἅμα δὲ πλεύμονα καὶ βράγχια οὐδὲν ὦπταί πω ἔχον.
But nothing has yet been seen having both a lung and gills at the same time.
Αἴτιον δ’ ὅτι ὁ μὲν πλεύμων τῆς ὑπὸ τοῦ πνεύματος καταψύξεως ἕνεκέν ἐστιν (ἔοικε δὲ καὶ τοὔνομα εἰληφέναι ὁ πνεύμων διὰ τὴν τοῦ πνεύματος ὑποδοχήν), τὰ δὲ βράγχια πρὸς τὴν ἀπὸ τοῦ ὕδατος κατάψυξιν· ἓν δ’ ἐφ’ ἓν ὄργανον χρήσιμον, καὶ μία κατάψυξις ἱκανὴ πᾶσιν.
And the reason is that the lung is for the sake of cooling by breath (and the name "lung" [pneumon] also seems to have been taken because of the reception of breath [pneuma]), while gills are for cooling from water; and one organ is useful for one purpose, and one cooling is sufficient for all.
Ὤστ’ ἐπεὶ μάτην οὐδὲν ὁρῶμεν ποιοῦσαν τὴν φύσιν, δυοῖν δ’ ὄντοιν θάτερον ἂν ἦν μάτην, διὰ τοῦτο τὰ μὲν ἔχει βράγχια τὰ δὲ πνεύμονα, ἄμφω δ’ οὐδέν.
So since we see that nature does nothing in vain, and if there were two, one or the other would be in vain, for this reason some have gills and others a lung, but nothing has both.
§11Ἐπεὶ δὲ πρὸς μὲν τὸ εἶναι τροφῆς δεῖται τῶν ζῴων ἕκαστον, πρὸς δὲ τὴν σωτηρίαν τῆς καταψύξεως, τῷ αὐτῷ ὀργάνῳ χρῆται πρὸς ἄμφω ταῦτα ἡ φύσις, καθάπερ ἐνίοις τῇ γλώττῃ πρός τε τοὺς χυμοὺς καὶ πρὸς τὴν ἑρμηνείαν, οὕτω τοῖς ἔχουσι τὸν πλεύμονα τῷ καλουμένῳ στόματι πρός τε τὴν τῆς τροφῆς ἐργασίαν καὶ τὴν ἐκπνοὴν καὶ τὴν ἀναπνοήν.
Since each of the animals needs food for its existence, but cooling for its preservation, nature uses the same organ for both of these, just as in some it uses the tongue for both tastes and expression, so in those that have a lung, it uses the so-called mouth for both the processing of food and for breathing out and breathing in.
Τοῖς δὲ μὴ ἔχουσι πνεύμονα μηδ’ ἀναπνέουσι τὸ μὲν στόμα πρὸς τὴν ἐργασίαν τῆς τροφῆς, πρὸς δὲ τὴν κατάψυξιν τοῖς δεομένοις καταψύξεως ἡ τῶν βραγχίων ὑπάρχει φύσις.
But for those that do not have a lung and do not breathe, the mouth is for the processing of food, while for cooling, in those that need cooling, the nature of gills is present.
Πῶς μὲν οὖν ἡ τῶν εἰρημένων ὀργάνων δύναμις ποιεῖ τὴν κατάψυξιν, ὕστερον ἐροῦμεν.
How, then, the power of the said organs produces cooling, we will say later.
Πρὸς δὲ τὸ τὴν τροφὴν μὴ διακωλύειν παραπλησίως τοῖς τ’ ἀναπνέουσι συμβαίνει καὶ τοῖς δεχομένοις τὸ ὑγρόν· οὔτε γὰρ ἀναπνέοντες ἅμα καταδέχονται τὴν τροφήν· εἰ δὲ μή, συμβαίνει πνίγεσθαι παρεισιούσης τῆς τροφῆς ἢ τῆς ὑγρᾶς ἢ τῆς ξηρᾶς ἐπὶ τὸν πνεύμονα διὰ τῆς ἀρτηρίας· πρότερον γὰρ κεῖται ἡ ἀρτηρία τοῦ οἰσοφάγου, δι’ οὖ ἡ τροφὴ πορεύεται εἰς τὴν καλουμένην κοιλίαν.
But with respect to not obstructing the food, a similar thing happens both to those that breathe and to those that receive liquid; for they do not receive food while breathing at the same time; otherwise, choking happens to occur by the food, either wet or dry, slipping in onto the lung through the windpipe; for the windpipe lies in front of the esophagus, through which food travels to the so-called belly.
Τοῖς μὲν οὖν τετράποσι καὶ ἐναίμοις ἔχει ἡ ἀρτηρία οἷον πῶμα τὴν ἐπιγλωττίδα· τοῖς δ’ ὄρνισι καὶ τῶν τετραπόδων τοῖς ᾠοτόκοις οὐκ ἔπεστιν, ἀλλὰ τῇ συναγωγῇ τὸ αὐτὸ ποιοῦσιν· δεχόμενα γὰρ τὴν τροφὴν τὰ μὲν συνάγει, τὰ δ’ ἐπιτίθησι τὴν ἐπιγλωττίδα.
Now, in quadrupeds and red-blooded animals, the windpipe has the epiglottis as a kind of lid; but in birds and in the oviparous of the quadrupeds, it is not present, but they perform the same thing by contraction; for when receiving food, the latter shut it by contraction, while the former put the epiglottis over it.
Προελθούσης δὲ τὰ μὲν ἐπαίρει, τὰ δὲ διοίγει καὶ καταδέχεται τὸ πνεῦμα πρὸς τὴν κατάψυξιν.
And when the food has passed, the former raise it, and the latter open it wide and receive the breath for cooling.
Τὰ δ’ ἔχοντα βράγχια, ἀφέντα διὰ τούτων τὸ ὑγρόν, διὰ τοῦ στόματος καταδέχεται τὴν τροφήν· ἀρτηρίαν μὲν γὰρ οὐκ ἔχουσιν, ὥστε ταύτῃ μὲν οὐθὲν ἂν βλάπτοιντο ὑπὸ τῆς τοῦ ὑγροῦ παρεμπτώσεως, ἀλλ’ εἰς τὴν κοιλίαν εἰσιόντος.
But those that have gills, having discharged the liquid through them, receive food through the mouth; for they do not have a windpipe, so that in this respect they would not be harmed by any slipping-in of the liquid, but it enters into the belly.
Διὸ ταχεῖαν ποιεῖται τὴν ἄφεσιν καὶ τὴν λῆψιν τῆς τροφῆς, καὶ τοὺς ὀδόντας ὀξεῖς ἔχουσι, καὶ καρχαρόδοντες σχεδὸν πάντες εἰσίν· οὐ γὰρ ἐνδέχεται λεαίνειν τὴν τροφήν.
Wherefore they make the discharge and the taking of food rapid, and they have sharp teeth, and almost all of them are saw-toothed; for it is not possible to grind the food.