471 a τὰ ἀναπνέοντα ἐκπνεῖν καὶ εἰσπνεῖν, ἐκπνεῖν δὲ μὴ ἐνδέχεται μηδὲν αὐτῶν, φανερὸν ὡς οὐδ᾿ ἀναπνεῖ αὐτῶν οὐδέν.
20III. Ἔτι δὲ τὸ φάναι τὸν ἀέρα ἕλκειν ἐκ τοῦ στόματος ἢ ἐκ τοῦ ὕδατος διὰ τοῦ στόματος ἀδύνατον· οὐ γὰρ ἔχουσιν ἀρτηρίαν διὰ τὸ πλεύμονα μὴ ἔχειν, ἀλλ᾿ εὐθὺς ἡ κοιλία πρὸς τῷ στόματί ἐστιν, ὥστ᾿ ἀναγκαῖον τῇ κοιλίᾳ ἕλκειν. τοῦτο δὲ κἂν τἆλλα ἐποίει ζῷα· νῦν δὲ οὐ ποιοῦσιν. 25κἂν ἐκεῖνα δ᾿ ἔξω τοῦ ὑγροῦ ὄντα ἐπιδήλως ἂν αὐτὸ ἐποίει· φαίνεται δ᾿ οὐ ποιοῦντ᾿ αὐτό. ἔτι πάντων τῶν ἀναπνεόντων καὶ ἑλκόντων τὸ πνεῦμα ὁρῶμεν γινομένην κίνησίν τινα τοῦ μορίου τοῦ ἕλκοντος, ἐπὶ δὲ τῶν ἰχθύων οὐ συμβαῖνον· οὐδὲν γὰρ φαίνονται κινοῦντες τῶν περὶ τὴν κοιλίαν, 30ἀλλ᾿ ἢ τὰ βράγχια μόνον, καὶ ἐν τῷ ὑγρῷ καὶ εἰς τὸ ξηρὸν ἐκπεσόντες, ὅταν σπαίρωσιν. ἔτι ὅταν 471 bἀποθνήσκῃ πνιγόμενα ἐν τοῖς ὑγροῖς πάντα τὰ ἀναπνέοντα, γίνονται πομφόλυγες τοῦ πνεύματος ἐξιόντος βιαίως, οἷον ἐάν τις βιάζηται χελώνας ἢ βατράχους ἤ τι ἄλλο τῶν τοιούτων γενῶν· ἐπὶ δὲ τῶν ἰχθύων οὐ συμβαίνει πειρωμένοις πάντα 5τρόπον, ὡς οὐκ ἐχόντων πνεῦμα θύραθεν οὐθέν. ὅν τε τρόπον λέγουσι γίνεσθαι τὴν ἀναπνοὴν αὐτοῖς, ἐνδέχεται καὶ τοῖς ἀνθρώποις οὖσιν ἐν τῷ ὑγρῷ συμβαίνειν· εἰ γὰρ καὶ οἱ ἰχθύες ἕλκουσιν ἐκ τοῦ πέριξ ὕδατος τῷ στόματι, διὰ τί τοῦτο οὐκ ἂν ποιοῖμεν καὶ οἱ ἄνθρωποι καὶ τἆλλα ζῷα; καὶ 10τὸν ἐκ τοῦ στόματος δ᾿ ἂν ἕλκοιμεν ὁμοίως τοῖς ἰχθύσιν. ὥστ᾿ εἴπερ κἀκεῖνα ἦν δυνατά, καὶ ταῦτ᾿ ἂν ἦν· ἐπεὶ δ᾿ οὐκ ἔστι, δῆλον ὡς οὐδ᾿ ἐπ᾿ ἐκείνων ἐστίν. πρὸς δὲ τούτοις διὰ τίν᾿ αἰτίαν ἐν τῷ ἀέρι
would then follow that, if respiring creatures must both exhale and inhale, and none of them can exhale, none of them can respire at all.
III. Again, to say that they draw in air from theThe physiology of the fish. mouth, or from the water by way of the mouth, is impossible; for since they have no lung, they have no windpipe: the stomach is close up to the mouth, so that they must draw in the air by the stomach. But then all other living creatures would do the same thing; which in fact they do not. Also fish would be seen to do so when they are out of the water; but obviously they do not. Again, in the case of all creatures which respire and draw breath, we see that there is some movement of the part which draws, but this does not happen with fishes; for we see them moving none of the parts about the stomach, but only the gills, both in water, and when they have been thrown out on to dry land, and gasp. Again, when any respiring animals die of drowning in water, bubbles of air violently expelled rise; e.g., if one holds down by force tortoises, or frogs, or anything else of such a kind; but it does not happen in the case of fishes, try as we will; which shows that they draw no breath from outside. But the mode of respiration which they attribute to fishes might also apply to men under water; for if fishes draw in air from the surrounding water by the mouth, why should not we men and all other animals do the same? We could also draw in the air from the mouth, like the fishes. If the one were possible, so also would the other be; but since it is not so in the one case, it is clear that it is not so in the other either. Besides, why is it that