18 ANIMAL INTELLIGENCE. 
exercise some discretion, involving a mental process, in the 
choice of a site for her web. She does not gaze with hungry 
longing upon the flies disporting themselves in the sunshine, 
speculating how, being wingless, she can capture those tooth- 
some, flying creatures. Indeed, it is probable that she cannot 
see them, for the visual powers of spinning, as distinguished 
from hunting, spiders are believed to be very feeble, being 
compensated for by an extraordinary refinement of the sense 
of touch. She simply sets to work to apply the specialised 
mechanism and material with which she is endowed to the 
purpose for which they are co-ordinated. Although cut off 
by the period spent as an egg in a cocoon from all parental 
instruction or example, she is at no loss for a plan. Innate 
functional impulse, which is probably the right definition of 
what we term ‘‘ instinct,’’ co-ordinate with certain specialised 
organs, directs the creature to the unconscious performance of 
certain definite acts without previous practice or experience. 
First the foundations are laid, in the shape of lines enclosing 
the area to be occupied by the web. From this circumfer- 
ence the radii or stays are drawn to the centre, whence the 
spider works outwards, stepping from stay to stay and laying 
down a thread in a wide spiral to act as scaffolding for the 
finished structure. Finally, having arrived at the limits of 
the operative net, she retraces her steps, working inwards in 
a much closer spiral, laying the transverse threads at the 
proper distance, and devouring, as she goes, the original 
scaffolding threads which enabled her to perform the work. 
If it is ditficult to dissociate such a consummate piece of 
engineering from the operation of a keen intellect, still more 
so is it to regard the infinitely greater complexity of the 
snares produced by certain other spiders as the mere product 
of functional automatism. Nevertheless, that seems to be 
the true explanation. If the spider’s web were the outcome 
of the creature’s individual ingenuity and intelligence there 
certainly would be manifest some variation in the design 
among millions of webs by different individuals of the same 
species—some imperfection in first attempts. No such varia- 
tion—no such imperfection—can be detected. There is no 
‘““°prentice hand ’’ among spiders. The first web of the 
