as each mother selected her house
at will and as I was unable to interfere in her choice, a narrow tube
would be colonized or not, according as the Osmia who owned it was or
was not able to make her way inside.

There remain some forty pairs of tubes with both galleries colonized.
In these there are two things to take into consideration. The narrow
rear tubes of 5 or 5 1/2 millimetres (.195 to .214 inch.--Translator's
Note.)--and these are the most numerous--contain males and males only,
but in short series, between one and five. The mother is here so much
hampered in her work that they are rarely occupied from end to end; the
Osmia seems in a hurry to leave them and to go and colonize the front
tube, whose ample space will leave her the liberty of movement
necessary for her operations. The other rear tubes, the minority, whose
diameter is about 6 millimetres (.234 inch.--Translator's Note.),
contain sometimes only females and sometimes females at the back and
males towards the opening. One can see that a tube a trifle wider and a
mother slightly smaller would account for this difference in the
results. Nevertheless, as the necessary space for a female is barely
provided in this case, we see that the mother avoids as far as she can
a two-sex arrangement beginning with males and that she adopts it only
in the last extremity. Finally, whatever the contents of the small tube
may be, those of the large one, following upon it, never vary and
consist of females at the back and males in front.

Though incomplete, because of circumstances very difficult to control,
the result of the experiment is none the less very remarkable.
Twenty-five apparatus contain only males in their narrow gallery, in
numbers varying from a minimum of one to a maximum of five. After these
comes the colony of the large gallery, beginning with females and
ending with males. And the layings in these apparatus do not always
belong to late summer or even to the intermediate period: a few small
tubes contain the earliest eggs of the entire swarm. A couple of
Osmiae, more forward than the others, set to work on the 23rd of April.
Both of them started their laying by placing males in the narrow tubes.
The meagre supply of provisions was enough in itself to show the sex,
which proved later to be in accordance with my anticipations. We see
then that, by my artifices, the whole swarm starts with the converse of
the normal order. This inversion is continued, at