38 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 
As many as one hundred and fifty or two hundred may be counted upon 
the tip of a single spinneret of an Epeiroid spider, as for example, Ar- 
giope cophinaria. These spinning spools are two jointed, at least they are 
divided into two parts, of which the base is the thicker, 
and sometimes the longer. ‘They are hollow 
tubes, through which the delicate ducts connected 
with the silk glands convey the liquid silk to the 
surface. These spinning spools are of several sizes and 
shapes (Fig. 26), and differ somewhat according to their 
Fras. 27,28, Viewor POSition upon the several spinnerets. ‘Thus those upon the 
a spinning spool anterior spinnerets have the basal part (bj) of a conical 
ace Tee shape and rather shorter than the point or terminal joint, 
ademata. (After tj, (Fig. 26 b, ce, compare with Fig. 27.) 
Sree Distributed here and there among these spools of ordi- 
nary size are a few which are larger and stouter, (Fig. 28.) In Argiope 
cophinaria there are three of these on each of the middle spinnerets, four 
upon each of the posterior, and one upon each of the anterior ones. A 
detailed description of these instruments will be given further on. 
These groups of spinning spools are surrounded by ranks of hairs and 
bristles (b, bb, br), both simple and branched, which are moyable and 
appear to have some important part in spinning. Possibly they 
serve to direct the course of the threads as they issue from the 
spools, or it may be that they form a protection to the more 
delicately organized spinning spools themselves. 
Il. 
The spinning spools are connected with a system of glands and ducts 
constituting the internal spinning organs, the reservoir within which is 
formed, and from which is secreted the material for all spinningwork. 
When the integument of the lower and front 
part of the abdomen is removed, to- 
gether with the thin layer of fat and 
the muscles that move the spinner- 
ets, a large bunch of minute vesicles 
visible to the naked eye in a large spider such 
as Argiope cophinaria is brought into view. 
Examined by the microscope they are found 
to be small, transparent, oval sacs. These are 
the silk glands. They are about one two-hun- 
dredth of an inch in diameter, in Epeira di- 
ademata (Meade); or 0.22 millimetre (Bucholz iiss 0 Wate i ae RT 
and Landois). In Argiope cophinaria they are tion of spinning glands in Hpeira di- 
of various lengths, averaging about (0.3 mm.)  ®4e¢mata._ (After Meade.) spn, spin- 
a nerets; py.g, pyriform, cy. g, cylindri- 
three-tenths of a millimetre. cal, tr.g, treeform, glands. 
Spinning 
Spools. 
Hairs and 
Bristles. 
Internal 
Spinning 
Organs. 
