1971] 
Jackson — W eb of Araneus 
25 
at the hub (Fig. 5b) resembling those on SS’s, raises the question 
of which glands are in operation as the hub is formed. 
Radius to Frame Connections and Y-Structures : 
In reading the following section the reader may refer to Table 5 
(R-F’s) and Table 6 (FY’s). In general appearance, R-F’s and 
Y-structures resembled each other more than they resembled other 
types of connections in the web. However, many of the structures 
we have already mentioned in the discussion of other types of thread 
connections were also found at these connections. 
We examined 8 R-F’s, 5 FY’s, and one RY. Each R-F (Fig. 6) 
and FY (Fig. 7) had one sleeve. Those at R-F’s were on the frame; 
those at FY’s were on the stem of the Y. The RY (Fig. 8) had 
2 sleeves. One was on the stem, and one was on an arm. Sleeves at 
R-Fs, FY’s and the RY were generally as long or longer than those at 
SS-R’s. 
R-F’s and the RY had many interconnected strands. Each R-F 
consisted of a multi-stranded radius fastened to a single stranded 
frame, except for two at which the frame was split into 2 strands 
at one side of the junction. Each FY consisted of a multi-stranded 
frame thread (one of the arms) fastened to a single stranded frame 
thread (one arm and the stem). One arm of the RY consisted of 
2 strands at the junction. Beyond the sleeve, the stem of the RY 
was split into several intertwined strands. 
Some frame threads at R-F’s and FY’s were thicker than any 
other threads from the web. The thickness of the arms of the RY 
(7 /x) was in the range of thickness (3 /x - 9 ji) found for radii at 
SS-R’s. 
Does the strength of a thread increase as its thickness increases? 
This seems likely because, generally, thread thickness corresponded 
directly with the importance of the supporting function of the 
thread (i.e., how large a portion of the web would collapse if it 
broke). Frames were thickest; radii from the trapping zone and at 
the RY were next; and radii and NS’s from the strengthening zone, 
PS’s, and SS’s were thinnest. 
Drag-line Attachment Disks: 
Whenever the spider moves about outside of its web, it continually 
plays out a drag-line which it periodically fastens to the substrate. 
The ampullate gland which is involved in the production of the 
scaffolding of the web (frames, radii, NS’s, and PS’s) is also involved 
