1974] 
Foelix — Spider Silk 
509 
spiral of orb weavers, however, can be revealed : The glue substance 
partially disintegrates under the electron beam and the two axial 
threads become clearly visible (Fig. 8). 
It is hoped that this simple technique will be usefully applied to 
morphological as well as taxonomical problems. 
References Cited 
Foelix, R. F. 
1970. Chemosensitive hairs in spiders. J. Morph. 132: 313-334. 
Friedrich, V. L. and R. M. Langer 
1969. Fine structure of cribellate spider silk. Amer. Zool. 9: 91-96. 
Lehmensick, R. and E. Kullmann 
1957. Feinbau der Fiiden einiger Spinnen. Zool. Anz. Suppl. 19: 123- 
129. 
Explanation of Figures on Opposite Page 
Fig. 1. Leg tip of Philodromus aureolus (nymph 2) as seen with the 
SEM. Scopula hairs (sc) surround the combed main claw. 1400 X. Inset: 
Scopula hairs bear fine extensions with terminal ‘end-feef. 4200 X- (Cour- 
tesy of Dr. W. Gnatzy). Fig. 2. The ‘end-feet’ of a scopula hair of 
Philodromus seen with the TEM. 7000 X. Fig. 3. Leg tip of Alopccosa 
accentuata (nymph 2) showing one main claw (M), chemosensitive hairs 
(c), mechanosensitive hairs (m) and a scopulate hair (sc). TEM, 630 X- 
Fig. 4. Scopulate hair of Micrommata virescens. Note the small end-feet. 
TEM, 4200 X. Fig- 5. Tip of a chemosensitive hair of Philodromus. Note 
the terminal pore opening (arrow). TEM, 12600 X- Fig. 6. Cribellate 
silk from Amaurobius ferox. The diameter of single threads is less than 
200 Little knobs become accentuated by the metal shadowing. TEM, 
28000 X- Fig. 7. Ecribellate silk from the silken cell of a Heliophanus. 
A mesh-work of fine fibers (0.1 n) underlies several stronger fibers (0.5 n). 
TEM, 2800 X, unshadowed. Fig. 8. Sticky spiral thread from Zygiella 
x-notata. The peripheral glue substance has precipitated around the double 
axial threads (arrow). TEM, 630 X- 
