§2.6.1Ἐστι δὲ καὶ ὁ μυελὸς αἵματός τις φάσις, καὶ οὐχ 6 ὧσπερ οἴονταί τινες, τῆς γονῆς σπερματικὴ δύναμις.
Bone marrow is also a certain form of blood, and not, as some believe, the seminal power of the generative fluid.
δηλοῖ δʼ ἐν τοῖς νέοις πάμπαν· ἅτε γὰρ ἐξ αἵματος συνεστύτων τῶν μορίων καὶ τῆς τροφῆς οὕσης τοῖς ἐμβρύοις αἵματος, καὶ ἐν τοῖς ὀστοῖς ὁ μυελὸς αϊματώόδης ἐστίν· αὐξανομένων δὲ καὶ πεττομένων, καθάπερ καὶ τὰ μὸρια μεταβάλλει καὶ τὰ σπλάγχνα τὰς χρὸας (ὑπερβολῇ γὰρ αίματῶδες καὶ τῶν σπλάγχνων ἕκαστόν ἐστιν ἔτι νέων ὄντων), οὕτω καὶ ὸ μυελὸς καὶ τῶν μὲν πιμελωδῶν λιπαρὸς καὶ πιμελῇ ὅμοιος, ὅσοις δὲ μὴ πιμελῇ ὅμοιος ἀλλὰ στέαρ γίνεται τὸ αἷμα πεττόμενον, τούτοις ὅὲ στεατωὅης.
This is completely clear in young animals; for since the parts are composed of blood and the food for embryos is blood, the marrow in the bones is also bloody; but as they grow and the food is concocted, just as the parts and the viscera change their colors (for each of the viscera is extremely bloody while they are still young), so too does the marrow change, and in those of a soft-fatty nature it becomes oily and like soft fat, while in those where the concocted blood becomes suet instead of being like soft fat, it becomes suety.
διὸ τοῖς μὲν κερατοφόροις καὶ μὴ ἀμφωδουσι στεατώδης, τοῖς δʼ ἀμφωόδουσι καὶ πολυσχιδέσι πιμελώδης.
Wherefore, in horned animals and those without teeth in both jaws it is suety, but in those with teeth in both jaws and many-cloven feet it is soft-fatty.
§2.6.22 ἥκιστα δὲ τοιούτος ὁ ῥαχίτης ἐστὶ μυελὸς διὰ τὸ δεῖν αὐτὸν εἶναι συνεχῆ καὶ διέχειν διὰ πάσης της ῥάέχεως διῃρημένης κατὰ τοὺς σφονδύλους· λιπαρὸς δ ὤν ἤ στεατώδης οὐκ ἄν ὁμοίως ἦν συνεχής, ἀλλʼ ἤ θραυστὸς ἤ ὑγρός.
2 But the spinal marrow is least of this kind, because it must be continuous and extend through the entire spine, which is divided by vertebrae; and if it were oily or suety, it would not be continuous in the same way, but would be either brittle or liquid.
ἔυια δʼ οὐκ ἔχει τῶν ζῷων ὡς ἀξίως εἰπεῖν μυελόν, ὅσων τὰ ὀστᾶ ίσχυρὰ καὶ πυκνά, οἷον τὰ τοῦ λέοντος· τούτου γὰρ τὰ ὀστᾶ, διὰ τὸ πάμπαν ἄσημον ἔχειν, δοκεῖ οἀκ ἔχειν ὅλως μυελόν.
And some animals do not have marrow to a degree worth mentioning, namely those whose bones are strong and dense, such as the lion; for the bones of this animal, because they have marrow in a completely unnoticeable amount, seem to have no marrow at all.
§2.6.33 ἐπεὶ δὲ τὴν μὲν τῶν ὀστῶν ἀναγκη φύσιν ὑπάρχειν τοῖς ζῴοις, ὴ τὸ ἀνάλογον τοῖς ὀστοῖς, οἷον τοῖς ἐνύδροις τὴν ἅκανθαν,ἀναγκαῖον ἐνίοις ὑπάρχει καὶ μυελόν, ἐμπεριλαμβανομένης τῆς τροφῆς ἐξ ἧς γίνεται τὰ ὀστᾶ.
3 Since the nature of bones (or what is analogous to bones, such as the spine in aquatic animals) must exist in animals, it is necessary that marrow also exists in some, because the food from which the bones are formed is enclosed.
ὅτι δʼ ἡ τροφὴ πᾶσιν αἷμα, είρηται πρότερον.
And that food is blood for all, has been said before.
εὐλόγως δὲ καὶ στεατώδεις οἱ μυελοὶ καὶ πιμελύδεις εἰσίν· διὰ γὰρ τὴν ἀλέαν τὴν γινομένην ὑπὸ τοῦ περιέχεσθαι τοῖς ὀστοῖς πέττεται τὸ αἷμα, ἡ δὲ καθʼ αὑτὸ πέψις αἵματος στέαρ καὶ πιμελὴ ἐστιν.
It is also reasonable that the marrow is suety and soft-fatty; for because of the warmth produced by being surrounded by the bones, the blood is concocted, and the concoction of blood by itself is suet and soft fat.
§2.6.44 καὶ ἐν τοῖς δὴ τὰ ὀστᾶ πυκνὰ ἔχουσι καὶ ίσχυρὰ εὐλόγως ἐν τοῖς μὲν οὐκ ἔνεστι, τοῖς δ ὀλίγος ἔνεστιν· είς γὰρ τὰ ὀστᾶ ἀναλίσκεται ἡ τροφή.
4 And indeed, in those that have dense and strong bones, it is reasonable that in some marrow is not present, and in others only a little is present; for the food is consumed into the bones.
ἐν δὲ τοῖς μὴ ἔχουσιν ὀστᾶ ἀλλʼ ἃκανθαν ὁ ῥαχίτης μόνος ἐστὶ μυελός· ὀλίγαιμα τε γὰρ φύσει ὑπάρχει ὄντα, καὶ κοίλη ἄκανθα μόνον ἡ τῆς ῥάχεής ἐστιν.
But in those that do not have bones but have a spine, only the spinal marrow is present; for they are by nature thin-blooded, and only the spine of the back is hollow.
διὸ ἐν ταύτῃ ἐγγίνεταιʼ μύνη τε γὰρ ἔχει χώραν, καὶ μόνη δεῖται συνδέσμου διὰ τὰς διαλήψεις.
Wherefore, it is produced in this; for only this has space, and only this needs a ligament because of the joints.
διὸ καὶ ὁ ἐνταῦθα μυελός, ὥσπερ είρηται ἀλλοιότερὸς ἐστιν· διὰ τὸ ἀντὶ περόνης γὰρ γίνεσθαι γλίσχρος καὶ νευρώδης ἐστίν, ἵνʼ ἕχῃ τάσιν.
Wherefore also the marrow here, as has been said, is of a different kind; for because it serves instead of a pin, it is viscid and sinewy, in order to have tension.
§2.6.55 διἅ τί μὲν σὖν μυελὸν ἔχει τὰ ζῷα τὰ ἔχοντα μυελόν, είρηται· καὶ τί ἐστιν ὁ μυελὸς, ἐκ τούτων φανερόν, ὅτι τῆς αἱματικῆς τροφῆς τῆς εἰς ὀστᾶ καὶ ἄκανθαν μερις ἐστὶ τὸ ἐμπεριλαμβανόμενον περίττωμα πεφθέν.
5 Why indeed those animals that have marrow have it has been said; and what marrow is, is clear from these things, namely that it is the part of the bloody food that goes into the bones and spine, being the enclosed residue that has been concocted.