§4.5.2424 σημεῖον δὲ τὸ συμβαῖνον ἐπὶ τῶν ἐχίνων· εὐθύς τε γὰρ γινόμενοι ἔχουσι καὶ ἐν ταῖς πανσελήνοις μᾶλλον, οὐ διὰ τὸ νέμεσθαι καθάπερ τινὲς οἴονται μᾶλλον, ἀλλὰ διὰ τὸ ἀλεεινοτέρας εἶναι τὰς νύκτας διὰ τὸ φῶς τῆς σελήνης.
24 And what happens in the case of sea-urchins is a proof; for they have them immediately upon coming into being, and even more at the full moon, not, as some think, because they feed more then, but because the nights are warmer on account of the light of the moon.
δύσριγα γὰρ ὄντα διὰ τὸ ἄναιμα εἶναι δέονται ἀλέας.
For being cold-sensitive on account of being bloodless, they stand in need of warmth.
διὸ καὶ ἐν τῷ θέρει μᾶλλων πανταχοῦ εὐθηνοῦσιν, πλὴν οἱ ἐν τῷ Πυρραίῳ εὐρίπῳ· ἐκεῖνοι δʼ οὐχ ἧττον τού χειμῶνος.
Therefore they thrive more everywhere in summer, except for those in the Pyrrhaean Euripus; and those thrive no less in winter.
αἴτιον δὲ τὸ νομῆς εὐπορεῖν τότε μᾶλλον, ἀπολειπόντων τῶν ἰχθύων τούς τόπους κατὰ ταύτην τὴν ὥραν.
The cause of this is that they have a greater abundance of food at that time, since the fish leave those places during this season.
§4.5.2525 ἔχουσι δʼ οἱ ἐχῖνοι πάντες ἴσα τε τῷ ἀριθμῷ τὰ ᾠὰ καὶ περιττά· πέντε γὰρ ἔχουσιν, τοσούτους δὲ καὶ τούς ὀδόντας καὶ τὰς κοιλίας.
25 And all sea-urchins have their eggs equal in number and odd; for they have five, and just as many teeth and stomachs.
αἴτιον δʼ ὅτι τὸ ᾠόν ἐστι, καθάπερ εἴρηται πρότερον, οὐκ ᾠὸν ἀλλὰ τοῦ ζῴου εὐτροφία.
And the cause is that the egg, as has been said before, is not an egg but the well-nourished state of the animal.
γίνεται δὲ τοῦτο ἐπὶ θάτερα μόνον ἐν τοῖς ὀστρέοις, τὸ καλούμενον ᾠόν.
And this, the so-called egg, arises only on one side in testaceans.
ταὐτὸ δὲ τοῦτό ἐστι καὶ τὸ ἐν τοῖς ἐχίνοις.
And this very same thing is also what is in sea-urchins.
§4.5.26ἐπεὶ τοίνυν 26 ἐστὶ σφαιροειδὴς ὁ ἐχῖνος, καὶ οὐχ ὥσπερ ἐπὶ τῶν ἅλλων ὀστρέων τοῦ σώματος κύκλος εἶς, ὁ δʼ ἐχῖνος οὐ τῇ μὲν τοιοῦτος τῇ δʼ οὔ, ἀλλὰ πάντῃ ὅμοιος (σφαιροειδὴς γάρ), ἀνάγκη καὶ τὸ ᾠὸν ὁμοίως ἔχειν.
Since, then, 26 the sea-urchin is spherical, and not, as in the case of other testaceans, having a single circle of the body, and since the sea-urchin is not of such a nature in one part but not in another, but is completely similar in every direction (for it is spherical), it is necessary that its egg also should be situated similarly.
οὐ γάρ ἐστιν, ὥσπερ τοῖς ἄλλοις, τὸ κύκλῳ ἀνόμοιον.
For its circumference is not dissimilar, as it is in the others.
ἐν μέσῳ γὰρ ἡ κεφαλὴ πᾶσιν αὐτοῖς· τῷ δʼ ἄνω τὸ τοιοῦτον μόριον.
For in all of them the head is in the middle, and this part is at the top.
§4.5.27ἀλλὰ μὴν οὐδὲ συνεχὲς 27 οἷόν τʼ εἶναι τὸ ᾠόν· οὐδὲ γὰρ τοῖ ἄλλοις, ἀλλʼ ἐπὶ θάτερα τοῦ κύκλου μόνον.
But indeed, neither is it possible for the egg to be continuous; 27 for neither is it so in the others, but only on one side of the circle.
ἀνάγκη τοίνυν, ἐπεὶ τοῦτο μὲν ἀπάντων κοινόν, ἴδιον δʼ ἐκείνου εἶναι τὸ σῶμα σφαιροειδές, μὴ εἶναι ἄρτια τὰ ᾠά.
Therefore, since this is common to all, but the spherical body is peculiar to the sea-urchin, it is necessary that the eggs should not be even in number.
κατὰ διάμετρον γὰρ ἂν ἦν, διὰ τὸ ὁμοίως δεῖν ἔχειν τὸ ἔνθεν καὶ ἔνθεν, εἰ ἦν ἄρτια καὶ κατὰ διάμετρον.
For if they were even and diametrically opposed, they would be situated diametrically, because the parts on this side and on that side must be similar.
οὕτως δʼ ἐχόντων ἐπ᾿ ἀμφότερα ἂν τοῦ κύκλου εἶχον τὸ ᾠόν.
But if this were so, they would have the egg on both sides of the circle.
τοῦτο δʼ οὐκ ἦν οὐδʼ ἐπὶ τῶν ἄλλων ὀστρέων· ἐπὶ θάτερα γὰρ τῆς περιφερείας ἔχουσι τὰ ὄστρεα καὶ οἱ κτένες τὸ τοιοῦτον μόριον.
Yet this was not the case even in the other testaceans; for oysters and pectens have this part on only one side of their circumference.
ἀνάγκη τοίνυν τρία ἢ πέντε εἶναι ἢ ἄλλον τινʼ ἀριθμὸν περιττόν.
Therefore, it is necessary that they should be three or five, or some other odd number.
§4.5.28εἰ μὲν οὖν τρία εἶχε, πόρρω λίαν ἦν, εἰ δὲ 28 πλείω τῶν πέντε, συνεχὲς ἄν· τούτων δὲ τὸ μὲν οὐ βέλτιον, τὸ δʼ οὐκ ἐνδεχόμενον.
Now, if it had three, they would be too far apart, and if 28 more than five, they would be continuous; and of these, the former is not better, and the latter is impossible.
ἀνάγκη ἄρα πέντʼ αὐτοὺς ἔχειν τὰ ᾠά.
Therefore, it is necessary that they should have five eggs.
διὰ τὴν αὐτὴν δ᾿ αἰτίαν καὶ ἡ κοιλία τοιαύτη ἔσχισται καὶ τὸ τῶν ὀδόντων τοσοῦ τόν ἐστι πλῆθος.
And for the same cause, the stomach also is divided in this way, and the number of teeth is just as many.
ἕκαστον γὰρ τῶν ᾠῶν, οἷον σῶμά τι τοῦ ζῴου ὄν, πρὸς τὸν τρόπον τὸν τῆς ζωῆς ὅμοιον ἔχειν ἀναγκαῖον· ἐντεῦθεν γὰρ ἡ αὔξησις.
For each of the eggs, being as it were a certain body of the animal, must necessarily have a similar relation to its way of life; for from this comes growth.
μιᾶς μὲν γὰρ οὕσης ἦ πόρρω ἂν ἦσαν, ἢ πᾶν ἂν κατεῖχε τὸ κύτος, ὥστε καὶ δυσκίνητον εἶναι τὸν ἐχῖνον καὶ μὴ πληροῦσθαι τῆς τροφῆς τὸ ἀγγεῖον· πέντε δʼ ὄντων τῶν διαλειμμάτων ἀνάγκη πρὸς ἑκάστῳ οὖσαν πενταχῆ διῃρῆσθαι.
For if the stomach were single, either they would be far apart, or it would occupy the whole cavity, so that the sea-urchin would be difficult to move and the vessel would not be filled with food; but since there are five intervals, it is necessary that, being situated at each of them, it should be divided in five ways.
§4.5.29διὰ τὴν αὐτὴν δʼ αἰτίαν καὶ τὸ 29 τῶν ὀδόντων ἔστι τοσοῦτον πλῆθος· τὸ γὰρ ὅμιοιον οὕτως ἄν ἡ φύσις εἴη ἀποδεδωκυῖα τοῖς εἰρημένονις μορίοις.
And for the same cause also is 29 the number of teeth so great; for in this way Nature would have assigned what is similar to the aforementioned parts.
διότι μὲν οὖν περιττὰ καὶ τοσαῦτα τὸν ἀριθμὸν ἔχει ὁ ἐχῖνος τὰ ᾠά, εἴρηται·
Why, then, the sea-urchin has its eggs odd and of this number, has been explained.
διότι δʼ οἱ μὲν πάμπαν μικρὰ οἱ δὲ μεγάλα, αἴτιον τὸ θερμστέρους εἶναι τὴν φύσιν τούτους· πέττειν γὰρ τὸ θερμὸν δύναται τὴν τροφὴν μᾶλλον, διόπερ περιττώματος πλήρεις οἱ ἄβρωτοι μᾶλλον.
But why some have them altogether small and others large, the cause is that the latter are warmer in their nature; for heat is better able to concoct the food, which is why the inedible ones are more full of residue.