§3.3Ἔτι δ’ ἐστὶν ᾠοτόκον τὸ τῶν ἰχθύων γένος.
Moreover, the class of fishes is also oviparous.
τούτων δὲ τὰ μὲν ἔχοντα κάτω τὴν ὑστέραν ἀτελὲς ᾠὸν τίκτει διὰ τὴν πρότερον εἰρημένην αἰτίαν, τὰ δὲ καλούμενα σελάχη τῶν ἰχθύων ἐν αὑτοῖς μὲν ᾠοτοκεῖ τέλειον ᾠὸν ἔξω δὲ ζῳοτοκεῖ, πλὴν ἑνὸς ὃν καλοῦσι βάτραχον· οὗτος δ’ ᾠοτοκεῖ θύραζε τέλειον ᾠὸν μόνος.
Among these, those that have the uterus low down lay an imperfect egg for the reason previously stated, while those of the fishes called selachia (cartilaginous fishes) produce a perfect egg within themselves but bring forth young alive externally, with the exception of one which they call batrachos (angler-fish); this one alone lays a perfect egg externally.
αἰτία δ’ ἡ τοῦ σώματος φύσις· τήν τε γὰρ κεφαλὴν πολλαπλασίαν ἔχει τοῦ λοιποῦ σώματος, καὶ ταύτην ἀκανθώδη καὶ σφόδρα τραχεῖαν.
The cause is the nature of its body; for it has a head many times larger than the rest of its body, and this head is spiny and extremely rough.
διόπερ οὐδ’ ὕστερον εἰσδέχεται τοὺς νεοττούς, οὐδ’ ἐξ ἀρχῆς ζῳοτοκεῖ· τὸ γὰρ μέγεθος καὶ ἡ τραχύτης τῆς κεφαλῆς ὥσπερ καὶ εἰσελθεῖν κωλύει, οὕτω καὶ ἐξελθεῖν.
Therefore, it neither receives the young back inside later, nor does it bring forth young alive from the beginning; for the size and roughness of the head prevent them from coming out, just as they prevent them from entering.
ἐπεὶ δὲ μαλακόδερμόν ἐστι τὸ ᾠὸν τὸ τῶν σελαχῶν (οὐ γὰρ δύνανται σκληρύνειν τὸ πέριξ· ψυχρότεροι γὰρ τῶν ὀρνίθων εἰσίν), τὸ τῶν βατράχων ᾠὸν μόνον στερεόν ἐστι καὶ στιφρὸν πρὸς τὴν ἔξω σωτηρίαν, τὰ δὲ τῶν ἄλλων ὑγρὰ καὶ μαλακὰ τὴν φύσιν· σκεπάζεται γὰρ ἐντὸς τῷ σώματι τῷ τῆς ἐχούσης.
Since the egg of the selachia is soft-skinned (for they cannot harden the surrounding shell, being colder than birds), the egg of the angler-fish alone is solid and firm for its safety outside, while those of the others are fluid and soft in nature; for they are sheltered inside the body of the mother that carries them.
ἡ δὲ γένεσις ἐκ τοῦ ᾠοῦ τοῖς τε βατράχοις ἔξω τελειουμένοις καὶ τοῖς ἐντὸς ἡ αὐτή, τούτοις δὲ καὶ τοῖς τῶν ὀρνίθων τῇ μὲν ὁμοία τῇ δὲ διάφορός ἐστιν.
Generation from the egg is the same for the angler-fish which develop to perfection outside and for those inside, and for these (fishes) and birds it is in some ways similar and in others different.
πρῶτον μὲν γὰρ οὐκ ἔχουσι τὸν ἕτερον ὀμφαλὸν τὸν εἰς τὸ χόριον τείνοντα, ὅ ἐστιν ὑπὸ τὸ περιέχον ὄστρακον.
For first, they do not have the second umbilical cord extending to the chorion, which is under the surrounding shell.
τούτου δ’ αἴτιον ὅτι τὸ πέριξ ὄστρακον οὐκ ἔχουσιν.
The cause of this is that they do not have a surrounding shell.
οὐδὲν γὰρ αὐτοῖς χρήσιμον· σκεπάζει γὰρ ἡ μήτηρ, τὸ δ’ ὄστρακόν ἐστι τοῖς ἐκτικτομένοις ᾠοῖς ἀλεώρα πρὸς τὰς θύραθεν βλάβας.
For it is of no use to them; since the mother protects them, whereas the shell is a protection against external injuries for eggs that are laid outside.
ἔπειθ’ ἡ γένεσις ἐξ ἄκρου μέν ἐστι τοῦ ᾠοῦ καὶ τούτοις, ἀλλ’ οὐχ ᾗ προσπέφυκε πρὸς τὴν ὑστέραν· οἱ γὰρ ὄρνιθες ἐκ τοῦ ὀξέος γίνονται, ταύτῃ δ’ ἦν ἡ τοῦ ᾠοῦ πρόσφυσις.
Secondly, for these also development is from the end of the egg, but not where it is attached to the uterus; for birds develop from the sharp end, and this was where the attachment of the egg was.
αἴτιον δ’ ὅτι τὸ μὲν τῶν ὀρνίθων χωρίζεται τῆς ὑστέρας, τῶν δὲ τοιούτων οὐ πάντων ἀλλὰ τῶν πλείστων πρὸς τῇ ὑστέρα προσπέφυκε τὸ ᾠὸν τέλειον.
The cause is that while the egg of birds is separated from the uterus, in these animals, not indeed in all but in most of them, the perfect egg remains attached to the uterus.
ἐπ’ ἄκρῳ δὲ γιγνομένου τοῦ ζῴου καταναλίσκεται τὸ ᾠόν, ὥσπερ καὶ ἐπὶ τῶν ὀρνίθων καὶ τῶν ἄλλων τῶν ἀπολελυμένων, καὶ τέλος πρὸς τῇ ὑστέρᾳ ὁ ὀμφαλὸς προσπέφυκε τῶν ἤδη τελείων.
As the animal develops at the end, the egg is consumed, just as in birds and other animals whose eggs are detached, and in the end, the umbilical cord of those already perfect is attached to the uterus.
ὁμοίως δ’ ἔχει καὶ ὅσων ἀπολέλυται τὰ ᾠὰ τῆς ὑστέρας· ἐνίοις γὰρ αὐτῶν, ὅταν τέλειον γένηται τὸ ᾠόν, ἀπολύεται.
The same is the case with those whose eggs are detached from the uterus; for in some of them, when the egg becomes perfect, it is detached.
ἀπορήσειεν ἂν οὖν τις διὰ τί διαφέρουσιν αἱ γενέσεις τοῖς ὄρνισι κατὰ τοῦτο καὶ τοῖς ἰχθύσιν.
One might therefore raise the question why the development in birds and in fishes differs in this respect.
αἴτιον δ’ ὅτι τὰ μὲν τῶν ὀρνίθων κεχωρισμένον ἔχει τὸ λευκὸν καὶ τὸ ὠχρόν, τὰ δὲ τῶν ἰχθύων μονόχροα, καὶ πάντῃ μεμιγμένον τὸ τοιοῦτον, ὥστ’ οὐθὲν κωλύει ἐξ ἐναντίας ἔχειν τὴν ἀρχήν· οὐ γὰρ μόνον κατὰ τὴν πρόσφυσίν ἐστι τοιοῦτον ἀλλὰ καὶ καταντικρύ, τὴν δὲ τροφὴν ῥᾷον ἕλκειν ἐκ τῆς ὑστέρας πόροις τισὶν ἀπὸ ταύτης τῆς ἀρχῆς.
The cause is that while the eggs of birds have the white and the yolk separated, those of fishes are of one color, and this substance is mixed throughout, so that nothing prevents them from having their starting-point from the opposite side; for not only at the attachment is it of this nature, but also on the opposite side, and it is easier to draw nourishment from the uterus by certain channels from this starting-point.
δῆλον δ’ ἐπὶ τῶν μὴ ἀπολυομένων ᾠῶν· ἐν ἐνίοις γὰρ τῶν σελαχῶν οὐκ ἀπολύεται τῆς ὑστέρας τὸ ᾠόν, ἀλλ’ ἐχόμενον μεταχωρεῖ κάτω πρὸς τὴν ζῳοτοκίαν, ἐν οἷς τελεωθὲν τὸ ζῷον ἔχει τὸν ὀμφαλὸν ἐκ τῆς ὑστέρας ἀνηλωμένου τοῦ ῳοῦ.
And this is clear in the case of those eggs that are not detached; for in some of the selachia the egg is not detached from the uterus, but, remaining held, moves down towards the viviparous birth, in which the animal, when perfected, has its umbilical cord from the uterus when the egg has been consumed.
φανερὸν οὖν ὅτι καὶ πρότερον ἔτεινον οἱ πόροι τοῦ ᾠοῦ ἔτι ὄντος περὶ ἐκεῖνο πρὸς τὴν ὑστέραν.
It is clear, then, that even earlier, while the egg was still around the animal, its channels extended to the uterus.
τοῦτο δὲ συμβαίνει, καθάπερ εἴπομεν, ἐν τοῖς γαλεοῖς τοῖς λείοις.
And this happens, as we said, in the smooth dogfish.
διαφέρει μὲν οὖν ἡ γένεσις κατὰ ταῦτα τῶν ἰχθύων τοῖς ὄρνισι, καὶ διὰ τὰς εἰρημένας αἰτίας· τὰ δ᾽ ἄλλα συμβαίνει τὸν αὐτὸν τρόπον.
In these respects, then, the generation of fishes differs from that of birds, and for the reasons mentioned; but in other respects it happens in the same way.
τόν τε γὰρ ὀμφαλὸν ἔχουσι τὸν ἕτερον ὡσαύτως ὥσπερ οἱ ὄρνιθες πρὸς τὸ ὠχρόν, οὕτως οἱ ἰχθύες πρὸς τὸ ὅλον ᾠόν (οὐ γάρ ἐστιν αὐτοῦ τὸ μὲν λευκὸν τὸ δ᾽ ὠχρόν, ἀλλὰ μονόχρων πᾶν), καὶ τρέφονται ἐκ τούτου, καταναλισκομένου τε ἐπέρχεται καὶ περιφύεται ἡ σὰρξ ὁμοίως.
For they have one of the two umbilical cords in the same manner as birds have theirs to the yolk, so fishes have theirs to the whole egg (for the egg is not part white and part yolk, but all of one color), and they are nourished from this, and as it is consumed, the flesh similarly comes over it and grows around it.