THE SNARE OF THE GIANT WOOD SPIDER. 
649 
distribute them evenly over the surface of her snare. Furthermore she would 
waste her material by collecting so large a number of radii all at one central 
point. She would only urmecessarily overburden that portion of her archi- 
tecture by placing there an excessive number of radii where a few would give 
sufficient strength. By making use of a branching system she obviates these 
defects. She adapts her architecture to the immensity of her snare. She 
simplifies her work ; she saves her material ; she more evenly distributes the 
strength of her scaffold ; she economizes her valuable time. 
The next point that needs consideration is the method by which the Nephila 
measures the distance between her spokes. For only by some geometrical 
operation could she produce so exact a work. The Araneus, I have said, per- 
forms the act in this way. She climbs out along a radius; she reaches the foun- 
dation-line; she takes four paces along it; and then affixes her thread. It is 
by the advance of four paces that she measures the interval between her spokes. 
By keeping strictly to this number she spreads her radii evenly through her 
snare. 
Now this method ^vill not suit the Nephila. If she made four paces between 
each pair of radii, then her spokes would be very widely spread, while it is 
essential that they should lie not far apart in order to support so large a wheel. 
She must adopt some other method, and this is how she gains her end. She 
moves out along the radius ; she reaches the foundation-line ; she advances 
along it. So far it is the same as the Araneus. But watch her hind leg. The 
claws at the tip are hooked over the radius along which she has just climbed 
out. She advances, but she does not release her clutch on the radius. As a 
consequence her hind leg becomes stretched tightly behind her. When this 
happens she lowers her spinnerets, anchors her filament, and secures a new 
spoke. She has measured off the distance for her first radius; it is the interval 
between her spinnerets and the tip of her hind leg! She now releases her hold . 
She again advances and hooks the same hind claws over the radius that she 
has just laid. She continues to advance until her leg is again outstretched in 
the same position as before. Once more she anchors her filament and the 
second radius is measured off. In this way she continues all round the snare, at 
every journey measuring a pair of spokes. AU her radii are evenly separated 
at the circumference, and the distance between the spinnerets and the tip of 
the hind leg is the simple measuring-rule employed. 
In this manner are the radii secured. I have tried to explain the various 
deviations, and to show the essential importance of each to the particular cha- 
racter of the snare. This laying of the radii is a wonderful sight. I know 
of no more striking architecture of its kind. Imagine, it is midnight in the silent 
woods. Before us is a great vertical wheel with a diameter as tall as a man. 
It is supplied with a hundred spokes, transparent, slender rays of silk which 
sparkle where we shine the light. Yet so delicate, they are all firm and strong ; 
yet so numerous, they are all geometrically exact; and they are spread abroad 
with perfect uniformity over all this immense sheet. Amidst them moves the 
great architect herself. She looks at first sight an unwieldy creature, groping 
aimlessly and fruitlessly with her limbs, and scrambling out over the invisible 
sheet as though she were climbing unsupported in the air. But it is not so. 
She is a marvellous and consummate architect. She works wdth a perfect 
regularity and precision; she weaves with an inimitable skill. Every movement 
of her widespread hmbs has a definite act in view. They are now feeling, now 
testing, now touching, now measuring ; they are building the most fascinating 
work of architecture that I have ever had the privilege to see. 
Let us pause. The construction of the radii is more than sufficient to engage 
our attention here. In the next chapter we will follow to its final completion 
the architecture of this geometrical snare. 
{to be continued.) 
