The fruit of the wild fig contains the psen, or fig-wasp. This
creature is a grub at first; but in due time the husk peels off and
the psen leaves the husk behind it and flies away, and enters into the
fruit of the fig-tree through its orifice, and causes the fruit not to
drop off; and with a view to this phenomenon, country folk are in
the habit of tying wild figs on to fig-trees, and of planting wild
fig-trees near domesticated ones.