of the sexes;
only, the series has a marked tendency to begin with females and to
finish with males.

The mother occupies herself at the start with the stronger sex, the
more necessary, the better-gifted, the female sex, to which she devotes
the first flush of her laying and the fullness of her vigour; later,
when she is perhaps already at the end of her strength, she bestows
what remains of her maternal solicitude upon the weaker sex, the
less-gifted, almost negligible male sex. There are, however, other
species where this law becomes absolute, constant and regular.

In order to go more deeply into this curious question I installed some
hives of a new kind on the sunniest walls of my enclosure. They
consisted of stumps of the great reed of the south, open at one end,
closed at the other by the natural knot and gathered into a sort of
enormous pan-pipe, such as Polyphemus might have employed. The
invitation was accepted: Osmiae came in fairly large numbers, to
benefit by the queer installation.

Three Osmiae especially (O. Tricornis, Latr., O. cornuta, Latr., O.
Latreillii, Spin.) gave me splendid results, with reed-stumps arranged
either against the wall of my garden, as I have just said, or near
their customary abode, the huge nests of the Mason-bee of the Sheds.
One of them, the Three-horned Osmia, did better still: as I have
described, she built her nests in my study, as plentifully as I could
wish.

We will consult this last, who has furnished me with documents beyond
my fondest hopes, and begin by asking her of how many eggs her average
laying consists. Of the whole heap of colonized tubes in my study, or
else out of doors, in the hurdle-reeds and the pan-pipe appliances, the
best-filled contains fifteen cells, with a free space above the series,
a space showing that the laying is ended, for, if the mother had any
more eggs available, she would have lodged them in the room which she
leaves unoccupied. This string of fifteen appears to be rare; it was
the only one that I found. My attempts at indoor rearing, pursued
during two years with glass tubes or reeds, taught me that the
Three-horned Osmia is not much addicted to long series. As though to
decrease the difficulties of the coming deliverance, she prefers short
galleries, in which only a part of the laying is stacked. We must then
follow the same mother in her migration from one dwelling to the next
if we would obtain a complete census of her family. A spo