Fish which swim in shoals are not much produced in the rivers, but are bred in the lakes, and they do as follows:—When there comes upon them the desire to breed, they swim out in shoals towards the sea; and the males lead the way shedding forth their milt as they go, while the females, coming after and swallowing it up, from it become impregnated: and when they have become full of young in the sea they swim up back again, each shoal to its own haunts. The same however no longer lead the way as before, but the lead comes now to the females, and they leading the way in shoals do just as the males did, that is to say they shed forth their eggs by a few grains at a time, and the males coming after swallow them up. Now these grains are fish, and from the grains which survive and are not swallowed, the fish grow which afterwards are bred up. Now those of the fish which are caught as they swim out towards the sea are found to be rubbed on the left side of the head, but those which are caught as they swim up again are rubbed on the right side. This happens to them because as they swim down to the sea they keep close to the land on the left side of the river, and again as they swim up they keep to the same side, approaching and touching the bank as much as they can, for fear doubtless of straying from their course by reason of the stream. When the Nile begins to swell, the hollow places of the land and the depressions by the side of the river first begin to fill, as the water soaks through from the river, and so soon as they become full of water, at once they are all filled with little fishes; and whence these are in all likelihood produced, I think that I perceive. In the preceding year, when the Nile goes down, the fish first lay eggs in the mud and then retire with the last of the retreating waters; and when the time comes round again, and the water once more comes over the land, from these eggs forthwith are produced the fishes of which I speak. Thus it is as regards the fish. And for anointing those of the Egyptians who dwell in the fens use oil from the castor-berry, which oil the Egyptians call kiki, and thus they do:—they sow along the banks of the rivers and pools these plants, which in a wild form grow of themselves in the land of the Hellenes; these are sown in Egypt and produce berries in great quantity but of an evil smell; and when they have gathered these some cut them up and press the oil from them, others again roast them first and then boil them down and collect that which runs away from them. The oil is fat and not less suitable for burning than olive-oil, but it gives forth a disagreeable smell. Against the gnats, which are very abundant, they have contrived as follows:—those who dwell above the fen-land are helped by the towers, to which they ascend when they go to rest; for the gnats by reason of the winds are not able to fly up high: but those who dwell in the fenland have contrived another way instead of the towers, and this it is:—every man of them has got a casting net, with which by day he catches fish, but in the night he uses it for this purpose, that is to say he puts the casting-net round about the bed in which he sleeps, and then creeps in under it and goes to sleep: and the gnats, if he sleeps rolled up in a garment or a linen sheet, bite through these, but through the net they do not even attempt to bite.