38 
THORAX, LEGS, AND WINGS. 
and pressure on the outside causing it to adhere. 
Dr. Rombouts (143) found there were on the under 
surface very minute hairs terminating in a kind of 
bulb, and from these flows an oily secretion which 
dries slowly and does not harden for a long time. He 
devised a very ingenius apparatus for examining the 
pulvilli by cutting a hole in a board and placing over 
it a glass. With the aid of a piece of paper gummed 
to the wings, the insect is introduced into the cavity 
in such a manner that the pulvilli rest on the glass. 
Then putting the board under the microscope with 
the glass side uppermost, this action was distinctly 
seen, as well as the liquid adhering to the glass. 
When the claws have no foothold on a smooth 
surface they slip sideways out of the way, and the 
pulvillus which stood folded up above them is now 
brought down, adhering in the way we have ex- 
plained. When the foot is lifted the pulvillus is 
stripped off the smooth surface and assumes its folded 
position again. The secretion being of an oily nature 
explains why bees cannot walk on smooth, moist sur- 
faces, where their claws cannot take hold. 
The Wings. 
The bee has four membranous wings. The anterior 
or front pair are attached to the meso-thorax, and the 
posterior or hind wings to the meta-thorax. In repose 
the wings lie horizontally over the abdomen, the 
anterior above and the posterior beneath (Figs. 2, 3, 
and 4), and so close to the body that they enable the 
bee to enter cells in the combs without any difficulty. 
