t of colour,
dropped on the Bee's thorax with a paint-brush while she is absorbed in
closing up the mouth of the tunnel, enables us to recognize the Osmia
in her various homes.

In this way, the swarm that resided in my study furnished me, in the
first year, with an average of twelve cells. Next year, the summer
appeared to be more favourable and the average became rather higher,
reaching fifteen. The most numerous laying performed under my eyes, not
in a tube, but in a succession of Snail-shells, reached the figure of
twenty-six. On the other hand, layings of between eight and ten are not
uncommon. Lastly, taking all my records together, the result is that
the family of the Osmia fluctuates roundabout fifteen in number.

I have already spoken of the great differences in size apparent in the
cells of one and the same series. The partitions, at first widely
spaced, draw gradually nearer to one another as they come closer to the
aperture, which implies roomy cells at the back and narrow cells in
front. The contents of these compartments are no less uneven between
one portion and another of the string. Without any exception known to
me, the large cells, those with which the series starts, have more
abundant provisions than the straitened cells with which the series
ends. The heap of honey and pollen in the first is twice or even thrice
as large as that in the second. In the last cells, the most recent in
date, the victuals are but a pinch of pollen, so niggardly in amount
that we wonder what will become of the larva with that meagre ration.

One would think that the Osmia, when nearing the end of the laying,
attaches no importance to her last-born, to whom she doles out space
and food so sparingly. The first-born receive the benefit of her early
enthusiasm: theirs is the well-spread table, theirs the spacious
apartments. The work has begun to pall by the time that the last eggs
are laid; and the last-comers have to put up with a scurvy portion of
food and a tiny corner.

The difference shows itself in another way after the cocoons are spun.
The large cells, those at the back, receive the bulky cocoons; the
small ones, those in front, have cocoons only half or a third as big.
Before opening them and ascertaining the sex of the Osmia inside, let
us wait for the transformation into the perfect insect, which will take
place towards the end of summer. If impatience get the better of us, we
can open them at the end of July o