ee ee ee ee ee Oe 
. liar Orb. 
, : 
THE ARMATURE OF ORBWEBS: VISCID SPIRALS. 91 
Thus Fig. 86 will represent a section of a snare upon which an Orb- 
weaver is spinning in her spirals. She has finished her task along the 
beaded line, BL, and is working upon a line L. Just beyond it, imme- 
diately behind her, the string numbered 5 shows a white unbroken surface ; 
No. 4 is slightly ruffled; in the string No. 3 a few points of segregation 
have begun to appear; at No. 2 the beads are nearly perfected on the part 
nearest the spider and quite finished on the further half. On string No. 1 
the beads are completely formed. The figure, although sketched from na- 
ture as far as it is possible to draw such swiftly changing objects, is neces- 
sarily in part diagramatic. However, it accurately expresses the facts. 
The beads when newly formed are of a white color, translucent and 
glistening. They are uniform in size, or nearly so, but there is a constant 
tendency in the first-formed minute beads to undergo a further process of 
aggregation, thus making 
larger beads. These large “ 
. R 
beads will often be found 
at the crossing of the lines. 
The effect of rain upon 
the beads is to blend sey- 
eral into one until quite 
large globules are = 
Beads —_ formed, in good aie 
Dissolved : Se BL 
by Rains, Part mixed with 
water. If the rain FiG. 86. Diagram illustrating the crystallizing of beads. SF, spiral 
A 4 “i foundation; BL, beaded line; L, line just spun; 2, 3, strings on 
be continued it dissolves the which beads are forming; SP, the spider. 
viscid material, and the 
portions which do not drop off remain as large beads. These also soon 
pass away, leaving the snare without the ordinary armature for efficient 
service. I have frequently tested this matter during and after heavy or 
long continued rains; and neither by tongue, nor touch of finger, nor con- 
tact with other objects, nor by glass could the beads be discovered on many 
of the spirals; and often the whole web is disarmed. This accounts for 
the fact that spiders find it necessary to construct new snares after pro- 
tracted rains. The rain also dissolves, but not quite so freely, the thick 
white shield and zigzag ribbon on the snares of Argiope. 
In this connection I introduce the explanation of a phenomenon which 
long greatly puzzled me. While wandering in the woods of Delaware 
County, I observed on several separate occasions, always in the 
snare of the Orchard spider (Argyroepeira hortorum), a novel and 
striking variation in the arrangement of the spirals, which is rep- 
resented at Fig. 87. It will be seen from this figure that the spiral space 
is divided into two distinct belts, of which the outer one contains about 
half the number of lines in the inner one. Of two specimens showing this 
appearance, the inner belt had sixteen and the outer eight, the difference 
A Pecu- 
