268 ON AERONAUTIC SPIDERS. 
a conclusion has been deduced. With this view, 
having procured some small branched twigs, I fixed 
them upright in glazed earthenware vessels with per- 
pendicular sides, containing water, their bases being 
immersed in the liquid, and upon them I placed 
several Aéronautic and Geometric Spiders. When- 
ever the animals thus circumstanced were exposed to 
a current of air, either naturally or artificially pro- 
duced, they directly turned the cephalothorax to- 
wards the quarter whence it came, even when it was 
so slight as scarcely to be perceptible; and elevating 
the abdomen, they emitted from their spinners a 
small quantity of glutinous matter, which was in- 
stantly carried out in a compound line, with a velo- 
city equal, or nearly so, to that with which the air 
moved, as was apparent from observations made on 
the motion of detached lines similarly exposed. The 
spiders, in the next place, carefully ascertained 
whether their lines had become firmly attached to any 
object or not, by pulling them with the first pair of 
legs; and if the result was satisfactory, after tighten- 
ing them sufficiently, they made them fast to the 
twigs; 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 constructing, 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 
