THE 



37 



br... 



s.ss 



..sp.c 



b-- 



du.c 



SW i! 



The spinnerets articulate 

 obliquely from the outer side 

 and the front, inward and 

 backward, so that their tips 

 approximate the correspond- 

 ing spinning fields of the mid- 

 dle spinnerets. The base is 

 covered on both of its side 

 faces with many rows of bris- 

 tles (Fig. 25, b) ; it is divided 

 from the terminal field by a 

 suture, su, and a brown chit- 

 inous zone, z. The terminal 

 joint is cap-shape, and is only 

 partially occupied as a spin- 

 ning field. 



On the top of the spinning 

 field are from sixty to seventy 

 very short spinning spools, 

 s.ss, and a spinning spigot, 

 connected with a cylindrical 

 gland, Fig. 25, sp.c. The base 

 of these spigots is surrounded FlG 

 by a pair of chitinized stripes, 

 which originate in the chit- 

 inous zone, z. Close to this 

 place is inserted a very strong 

 and long sinew, sw, which unites w r ith the chitinous border of the spin- 

 ning field at the furrow (su) between the base and the terminal joint. 

 This sinew passes beyond the root of the spinneret into the strong, motor 



muscle, ms, which controls the movement of 

 the spinneret towards its fellows. Within the 

 bases of the spinnerets are bundles of muscles 

 which contribute both to the general move- 

 ment of the spinneret and to the movement 

 of the individual spools on the tip. On the 

 chitinous edge of the spinning field is a single 

 row of strong bristles, br. 



On examining the spinnerets with a lens 

 of ordinary power, the tips or spinning fields 

 are found to be covered with a great number 



FIG. 26. View of the spinning spools of 111 



Argiope cophinaria, as they appear in of fine movable Spinning tubes, already men- 

 clusters a.shortspoolsjc^ongspools; tioned known as spinning spools (Fig. 26), 



b, a small cluster ; tj, terminal joint ; 



bj, basai joint. which are regularly disposed over the surface. 



-^ 



Anterior spinneret, magnified largely, z, brown chit- 

 inous zone that bounds the spinning field ; sw, sinew of the 

 bending muscles of the anterior spinning wart ; du.c. duct 

 from cylindrical spinning glands ; sp.c, spigot discharging cy- 

 lindrical gland ; sp.t, spigot of treeform gland ; s.ss, spinning 

 spools of pyriform glands. (Bucholz and Landois.) 



