i8 
Psyche 
[March-June 
the junction plus the threads in the immediate vicinity of the junction. 
The point at which the SS joined one side of the radius was either 
directly across from where it joined the other side (zero-junction) 
(Fig. 2a) ; or there were varying amounts of space (the junction) 
along the radius between these points (non-zero junction) (Fig. 2b), 
causing the SS to have a disconnected appearance. In contrast to 
the SS’s, radii always appeared as continuous, nearly straight lines 
at SS-R’s. Junctions were smooth (Fig. 2b) or rough (Fig. 2c), 
with many gradations between. The smoother junctions were more 
prevalent. 
It would be interesting to know in what way, if any, the length 
and roughness of the junction are related to the functioning of the 
web. For example, do these features affect the strength of the con- 
nection or the transmission of vibrations along the radius? 
The radius at the frame side of all SS-R’s and, less frequently, 
the radius at the hub side of a SS was rougher in appearance and 
thicker adjacent to the junction than the same thread further away 
from the junction. These areas will be referred to as sleeves (Fig. 
2d). For any given junction, the sleeve on the radius at the frame 
side was at least 25 jjl longer than the one on the radius at the hub 
side; and usually it was longer than the one on the SS. 
Perhaps threads are strengthened by sleeves, and the prevalence 
and length of sleeves are related to the magnitude of the tensions 
they must withstand in the web. Measurements of these tensions 
would be useful. At some SS-R’s, the SS joined the radius as a 
single strand at both sides of the junction (Fig. 2b and 2d). Other 
SS-R’s consisted of various numbers of strands (Fig. 2a, 2c, and 2e), 
often interconnected and variable in thickness. Perhaps the presence 
of many strands at a junction functions in the dispersal of stresses 
or to increase elasticity. 
If the presence or absence of non-zero junctions, sleeves on the 
radii at the hub side of junctions, sleeves on SS’s, and many strands 
at the connection improve the web in some way, why do some SS-R’s 
have these characteristics while others do not? 
Many SS-R’s had idiosyncrasies, the description of which will 
not be attempted here. The doughnut shaped structure in Fig 2b 
is an example. It does not seem likely that these structures have a 
specific function since any one of them occurred at only a single SS-R. 
They are probably artifacts of the forces acting on the connection 
during its formation. Thread connections, especially SS-R’s, are 
produced at a very rapid rate. The spider produces over a thousand 
