15 
1971] Jackson — Web of Araneus 
relation was apparent between these factors and structural features 
of the connections. 
The day before the connections in a spider’s web were to be looked 
at, the glass doors were removed, and the old web was destroyed. 
The new web, built by the spider early the next morning, was treated 
as in Witt et al . (1968) except that the threads were not coated in 
any way. Afterwards several thread connections from the web 
were examined. 
In the web, threads are stretched tight into straight lines. When 
placed on a glass slide, threads with sticky globules often remained 
straight; but the globules were usually destroyed. Threads without 
globules curled and twisted when placed on a slide. To obtain a 
less distorted connection to study under a microscope, Permount 
mounting medium (Fisher Scientific Company) was streaked into 
a circle on a glass microscope slide, forming a basin. The slide was 
then placed against the web so that the threads surrounding the 
connection would stick to the Permount. Thus, the connection was 
suspended above the slide by the ridges of the circle of Permount. 
The threads were then burned loose from the outer edges of the 
circle by a surgical cauter, and the slide was taken away. The 
slide was always made on the same day that the web was built. 
Within a week of preparation of the slide, the connection was 
viewed under a Leitz Labolux D microscope; and negatives were 
made on Panatomic X sheet film using a Brinkmann Mark V camera 
with various objective lenses on the microscope. That structural 
Fig. 1. The vertical orb web of Araneus dladematus with labeled struc- 
tures. The scale, consisting of a weight suspended by cotton threads 20 
mm apart, indicates size and vertical direction. Abbreviations: SS, loop of 
sticky spiral; SS-R, sticky spiral to radius connection; NS-R, non-sticky 
spiral to radius connection; R-F, radius to frame connection; FY, frame 
Y-structure; RY, radial Y-structure. 
Fig. 2a-d. Examples of sticky spiral (SS) to radius connections. In these 
photomicrographs, SS’s run vertical ; radii, horizontal. Radius is fastened 
to frame to right of page. Up and down on page corresponds to up and 
down, with respect to gravity, in web. a. Zero junction: points where SS 
joins radius on one side is directly across from where it joins at other 
side. Note sleeves on radius at both frame and hub side of SS. b. Smooth 
non-zero junction: there is space, smooth in appearance, along radius be- 
tween points at which SS joins each side of radius. Idiosyncrasies such as 
the doughnut-shaped structure in this SS-R made generalization about 
structure difficult, c. Non-zero junction with rough appearance, d. Note 
sleeves (S) on radius at frame side of SS and on SS, loose strands (L) 
on radius, and globules (G) on SS. 
