§20 INSTINCT OF INS&CTS. 
in a hollow tree, their natural residence. The conclusion, 
then, seems irresistible, that reason must have been their 
guide, inducing a departure from their natural instinct 
as extraordinary as would be that of a hen which should 
lay her eggs in a hot-bed, and cease to sit upon them. 
The adaptation of means to an end not likely to have 
been provided for by instinct, is equally obvious in the 
ingenious mode by which a nest of humble-bees propped 
up their tottering comb, the particulars of which having 
before mentioned to you*, I need not here repeat. 
There is perhaps no surer criterion of reason than, 
after having tried one mode of accomplishing a purpose, 
adopting another more likely to succeed. Insects are 
able to stand this test. A bee which Huber watched 
while soldering the angles of a cell with propolis, detach- 
ed a thread of this material with which she entered the 
cell. Instinct would have taught her to separate it of 
the exact length required; but after applying it to the 
angle of the cell, she found it too long, and cut off a por- 
tion so as to fit it to her purpose”. ji 
This is a very simple instance; but one such fact is as 
decisive in proof of reason as a thousand more complex, 
and of such there is no lack. Dr. Darwin (whose autho- 
rity in the present case depending not on hearsay, but his 
own observation, may be here taken,) informs us, that 
walking one day in his garden he perceived a wasp upon 
the gravel walk with a large fly nearly as big as itself 
which it had caught. Kneeling down he distinctly saw 
it cut off the head and abdomen, and then taking up with 
its feet the trunk or middle portion of the body to which 
@ Vou. I. 4th Ed. 379. > Huber, i1. 268. 
