456 Mr. BLackwaLL’s Observations to ascertain 
next place, carefully ascertained whether their lines had become 
firmly attached to any object or not, by pulling at them with 
the first pair of legs; and if the result was satisfactory, after 
tightening them sufficiently they made them fast to the twig ; 
then discharging from their spinners, which they applied to the 
spot where they stood, a little more of their liquid gum, and 
committing themselves to these bridges of their own construct- 
ing, they passed over them in safety, drawing a second line after 
them as a security in case the first gave way, and so effected 
their escape. 
Such was invariably the result when the spiders were placed 
where the air was liable to be sensibly agitated: I resolved 
therefore to put a bell-glass over them ; and in this situation 
they remained seventeen days, evidently unable to produce a 
single line by which they could quit the branch they occupied 
without encountering the water at its base ; though on the re- 
moval of the glass they regained their liberty with as much 
celerity as in the instances already recorded. 
This experiment, which from a want of due precaution in its 
management has misled so many distinguished naturalists, I 
have tried with several of the geometric spiders, and always 
with the same success. Placed under the bell-glass, or in any 
close vessel, they in vain endeavoured to make their escape 
from the branch to which they were confined; but in the dis- 
turbed air of an inhabited room they readily accomplished their 
object. 
Instances of long-sustained abstinence from food by insects of 
the genus Aranea, unaccompanied by any manifest diminution of 
vital energy, have been given by various observers. In adding 
another case to the list it is proper to remark, that it must be | 
received solely on my own authority. 
Some of the spiders which produce gossamer were procured 
on 
