THE SPINNING ORGANS. 35 
about equal in length. In form these organs are somewhat conical and 
cylindrical, widened at the base and gently sloped or flattened at the tips. 
The three pairs differ somewhat in appearance and size, the mid- 
dle pair being shorter and less in size and more closely approx- 
imated. The posterior and anterior spinnerets haye two joints 
(Bucholz and Landois); the middle ones are unjointed cones.!| They are 
movable, particularly the posterior and anterior pairs, articulating with the 
integument of the body, and can 
be closed in upon each other until 
the tips touch at the spinning fields, ly 
as when one closes the thumb upon \ NN 
the four fingers of his hand. The Vi bea, A 
spinning fields, Fig. 21, SF, are 
The Spin- 
nerets. — 
E ; ; ey SF 
those portions of the tips and sides : ie 
of the spinnerets on which are 
placed the sessile tubes out of ri 
which the silk passes. 
In repose the spinnerets are gen- | \ 
erally closed (Fig. 21), forming a 
sort of rosette of five divisions; but 
when the spider is engaged in ac- 
tive operations, the posterior and 
as 
eae: 
anterior spinnerets are thrown well i 
back, and the two middle oe 
1. Poste- ones open up, and thus, Kh 
mor Ebia- + auote the lanpdage of Ney 
nerets. a eas ve 
Dugés, “this singular flow- 
er unfolds.” The posterior spinner- k 
ets (Figs. 21 and 23, P)? are well 
separated from each other, and lie 
directly forward of the semilunar Fic. 23. Posterior spinneret of Ep. diademata, greatly 
] : Fi 91. TI magnified. su, sutine between joints; SF, spinning 
anal covering ( 1g. , ac). 1ey field; bb, branched bristles; sb, simple bristles; sp, 
are movable horizontally toward spigot spool; l.ss, long spinning spools; s.ss, short 
spools. (After Bucholz and Landois.) 
each other, so that their long oval 
_ spinning fields approximate and, indeed, may be said to lie upon the cor- 
responding middle spinnerets. They may be described as thumb shaped 
organs; are of a long, cylindrical form, and towards the free end are con- 
ically rounded. The terminal joint is divided from the base by a suture, 
Fig. 23, su, which extends along the inner and hinder edge, much farther 
? oT > 
than on the opposite edge, so that the spinning field extends on that face 
much farther towards the base. 
' Meckel and Oeffinger both attribute three joints to the posterior and anterior, and two 
to the middle spinnerets. 
*To prevent confusion and the multiplication of references to figures the same letter 
ing is preserved for like organs and parts thereof in all the anatomical figures. 
