THE ARMATURE OF ORBWEBS: VISCID SPIRALS. 87 
certainly made a mistake in saying that the suspensory lines are as often 
studded with beads as the spirals.1 The radii are often found more or 
less beaded, although this is a rather exceptional and incidental condition ; 
but I cannot recall, among the vast number of orbwebs, a single instance 
of beads upon the suspensory or foundation lines. The dewdrops gather 
on those lines, however, and perhaps Rennie, like some other observers, 
was deceived by them. 
Under the microscope the beads show as beautiful objects, not unlike 
pearls strung upon a cord, Indeed, were a jeweler to reproduce in exact 
: form and suitable magnitude a geometric web, substituting pearls 
ane for beads, he would have a necklace of surpassing beauty. The 
beads vary in size according to the size of the orb and its maker; 
they vary also upon the same orb and 
line. Some have a thickness little greater 
than the diameter of the line; others are 
several times greater, say in proportion of 
6, 3,4, and 2. The larger ones commonly ®-6-@-2- G00 @e2.Q@0® 
alternate with the smaller, two or more of 
the latter succeeding the former, and this iS ili 
sequence is tolerably constant, but it is by 76; Ps ee 
no means absolute. Immediately after for- Iv 
I> So OO -w2-2<@>- 
mation the beads are uniform in size, and 
the change in size is afterward caused prob- 
ably by the interblending of two or more 
of the original beads. (See Fig. 84.) 
They are for the most part semitrans- 7.8 Relative ale and shapes of viscid 
beads. The space beaded at IV is shown 
parent or translucent. Frequently there ata, natural size. 
occur what appear to be opaque beads, 
showing quite black upon the line; these are simply particles of dust, 
around which a delicate coating of the spiral gum has gathered. Small 
spherical objects, grains of pollen and the like, also are seen, and the orb 
soon becomes well sprinkled over with minute extraneous particles, espe- 
cially if the wind blows or the location is dusty. Under the microscope 
the beaded line shows through the substance of the globules, which is 
evidently aggregated around it. Indeed, one may scrape off the beads and 
leave the line intact. Fig. 84 shows a few of these viscid beads as they 
appear under a microscope. The sections I, II, III are from a snare of 
Cyclosa caudata examined afield, Section IV is drawn from a snare of 
Argiope argyraspis spun while in confinement. It shows the beading 
along a space of nearly five millimetres as marked off at a; and also indi- 
cated upon the magnified line. None of the beads upon this snare were 
longer than about one-tenth of a millimetre. In shape they were ovoid, 
more or less pointed at the poles; many were globular and some had 
, 
1 Insect Architecture, page 313, 
