ODeaC rc Bh Vy . 
THE ARMATURE OF ORBWEBS: VISCID SPIRALS. 
i. 
THE next step in orbmaking is to prepare for the spinning of the con- 
centric lines or spirals. This is done by starting a line at or near the 
notched zone and carrying it around spirally toward the cirecum- 
mraete ference, attaching it by the spinnerets to the intersected radii, 
ae pee This forms the spiral scaffolding. The distance between these 
lines is about equal to the width of the notched zone, the space 
between which and the first scaffold spiral is in fact the free zone. The 
absolute width differs of course according to the size of the web. In large 
orbs of Epeira domiciliorum from which the explanatory figure (Fig. 77) was 
drawn, the distance was about an inch between any two of the eight spirals 
(I-VIIT) except between I-II, where it was 
about three-fourths of an inch. These wide 
spirals, as will presently be seen, are the 
scaffolding upon and by which the true 
spirals are laid in, and from which they 
differ by being destitute of viscid beads. 
Before the beaded spirals are spun, 
however, which is the completion of the 
snare, a preliminary act some- 
times occurs. Very many orb- 
webs are not perfect orbs; in 
some the entire space circumscribed by the 
. foundation lines and the foliage or other 
Fig.77. Spiral scaffolding. LinesI-Villare objects to which they are attached, is filled 
the scaffold ; ix, a section filled in; x, cor- Gate - sy 
ner loops. with true viscid spirals, thus nearly elimi- 
nating the Foundation Space proper. In 
other orbs only the lower part of the snare is netted with spirals to the 
very foundation lines. In others again the angles formed by the interior 
margin of the Foundation Space (the inner foundation lines) represented 
by letters ix and x, in the figure, are filled with spirals. In such cases 
these corners or angles have usually been covered first. For example, in 
the orb at Fig. 77 the animal first spun the spirals which fill up the 
angle ix. She then passed to the right hand corner x which was in like 
(79) 
Corner 
Loops. 
