THE SNARE OF THE GIANT WOOD SPIDER. 
647 
slack line which is drawn down cannot again be absorbed into the spinnerets 
and is thus permanently lost. 
As was observed in the case of the foundation-lines, so also is the single filament 
of suspension formed by the fusion of a number of threads. They can be seen 
escaping in a delicate cluster from the very front of the spinnerets. Now occa- 
sionally, while the Nephila is suspended in the air, she gives forth another filament 
which she permits to float away upon the breeze. She has failed to find an at- 
tachment with her long and raking limbs, and now she begins to search the 
air by the aid of an extensive line. But let us observe the act in a little detail. 
We will first detect the fact that the line given to the wind escapes from the 
posterior spinnerets, while the suspension line emerges from those in front. 
Excellent arrangement. The line given to the wind must float away behind 
the spider. Did it not come from the hindmost spinnerets then it would get 
entangled in the suspension line. But there is another point. The flotation line, 
that is the one given to the wind, is, like the suspension line, not a single but a 
complex thread. Yet its composition is the exact reverse of the suspension 
line. It emerges as a single filament and ends in a cluster of threads. This 
terminal brush is the aerial support which permits it to float freely on the breeze. 
This little fact I have elsewhere described. The new point revealed by the 
Nephila is that the spider can emit at the same moment two lines constructed 
on a reverse plan. The one is from the front of her spinning wheel ; it is a fixed 
suspension line composed of a cluster of strands which fuse into a single thread. 
The other escapes from the hindmost spinnerets ; it is a free flotation line con- 
sisting of a single filament which terminates in a sheaf of threads. What a 
wonderful and efficient spinning apparatus to produce such diverse work as this ! 
I pass now to the next stage in the architecture, the method by which the radii 
are distributed through the snare. Remember first the work of the Araneus. 
She spreads abroad her radiating spokes, about twenty in a moderate snare. 
They are all equidistant; they all diverge evenly from a common centre ; they 
form a perfect and symmetrical wheel. Now let us follow the Nephila, and see 
how she varies from the common plan. Like the Araneus she lays her radii 
haphazard ; a few on one side, then a few on the other, without working on any 
apparent scheme. The Araneus fixee her radii in this manner. She climbs 
out along one radius paying out her tilawent behind her ; she reaches the found- 
ation-line ; she takes four paces along that line there she halts, draws tight her 
filament, secures it to the foundation line , and her radius is in place. She then 
climbs back along this new radius, anchors her thread at the centre, and thus 
duplicates her spoke. Now, in what way does the Nephila act ? She also climbs 
out from the centre to the circumference, but in the first half of the journey 
she clings to a pair of radii; then she drops one of the two, and in the same way 
as the Araneus continues her climb to the end. An essential difference now 
occurs. She does not, like the Araneus, move forward four paces, fix her line, 
and then climb back again along it. She advances a distance of one inch, anchors 
her filament, and the radius is in place. But she does not halt here and return 
to the centre. She makes a second advance over an equal distance. Then she 
again fixes a line. This done, she climbs back along an adjoining radius, and at 
its inner end she attaches her thread. Thus, as a result of the return journey, a 
second radius in in place. This is therefore a very different mechanism from 
that employed in the ordinary snare. The Araneus at each journey to and 
from the centre lays out only one radius, but, since she climbs back along her 
new spoke, she manufactures it of double strength. The Nephila in the same 
journey constructs two radii, but since she returns along an adjoining radius, 
therefore each consists of only a single line. 
Now for another difference. All the radii in the snare of the Araneus diverge 
evenly from the centre in the same way as a series of spokes radiate from the 
hub of a wheel. It is otherwise in the architecture of the Nephila. She supplies 
