222 MEANS BY WHICH ANIMALS ADHERE 
observed that individuals sometimes remained fixed 
to the sides of an exhausted glass receiver after they 
had entirely lost the power of locomotion, and an 
evident distention of the abdomen had been occa- 
sioned by the expansion of the aériform fluids it 
contained. To detach them from those stations the 
employment of a small degree of force was found 
requisite. This occurrence, which first suggested to 
me the true cause of the phenomena under consider- 
ation, induced me to prosecute the inquiry more 
extensively than I had hitherto done. Selecting clean 
phials of transparent glass, I placed in them spiders 
and various insects in the larva and imago states, 
capable of walking on their upright sides. I then 
breathed into the phials till the aqueous vapour ex- 
pelled from the lungs was copiously condensed on 
their inner surface. The result was remarkable. The 
moisture totally prevented those animals from obtain- 
ing any effectual hold on the glass; and the event 
was equally decisive if a small quantity of oil was 
substituted for the aqueous vapour. A similar con- 
sequence ensued also when the flour of wheat, or 
finely pulverized chalk or gypsum, was thinly distri- 
buted over the interior surface of the phials, the 
minute particles of those substances adhering to the 
tarsal brushes of the spiders, the pulvilli of the perfect 
insects, and the underside of the feet of the larvee. 
These facts appeared quite inexplicable, except on the 
supposition that an adhesive secretion is emitted by 
