218	SCIENCE
beam, which would certainly prove the larva*s
undoing by interfering with its growth? She
could, for just now we saw her drag out and
throw away, at a' distance, a similar beam*
She could and she doesn't. She closes the cell,
cements the lid, seals up the straw in the thick-
ness of the mortar. More journeys are taken, not
a few, in search of the cement required to
strengthen the cover. Each time, the mason ap-
plies the material with the most minute care,
while giving the straw not a thought. In this
way, I obtain, one after the other, eight closed
cells whose lids are surmounted by my mast,
a bit of protruding straw. What evidence of
obtuse intelligence!
This result is deserving of attentive considera-
tion* At the moment when I am inserting my
beam, the insect has its mandibles engaged: they
are holding the pellet of mortar Intended for the
blocking-operation. As the extracting-tool is not
free, the extraction does not take place, I ex-
pected to see the Bee relinquish her mortar
and then proceed to remove the encumbrance. A
dab of mortar more or less is not a serious busi-
ness* I had already noticed that it takes my
Mason-bees a journey of three or four minutes
to collect one. The pollcn«expeditions last longer,
a matter of ten or fifteen minutes. To drop her
pellet, grab the straw with her mandibles, now
disengaged, remove it and gather a fresh supply