CHAPTER LS 
THE SPINNING ORGANS. 
Ik 
Tne external spinning organs or spinning fingers, are located under the 
posterior or apical extremity of the abdomen in most species. In some, 
however, they are placed a little more underneath, and in such 
External genera as Acrosoma and Gasteracantha they are located at or near 
Sea the middle point of the ventral part of the abdomen, forming 
rgans. ; : Atlas 
the apex of the inverted pyramid or cone, which it then assumes. 
In the orbweaving species the external spinning organs consist ordinarily 
of six spinnerets, which are 
divided into pairs arranged 
symmetrically on either side 
of the median line of the 
venter, occupying a small cir- 
cular space immediately for- 
ward of the anal opening. The 
hindermost pair (nearest the 
Fig. 22. The spinnerets in 
situ, completely separated 
Fic. 21. View of the spinnerets of apex), will be known in this 
Argiope cophinaria, represented Work as the posterior or outer 
closed, but the parts not quite in a . : 
contact, A, anterior, P, posterior, Sp mnerets ? the foremost pair; 
M, middle spinnerets. SF, spin- as the anterior or inner spin- 
and feebly magnified, bent 
back and flattened. ac, 
semilunar anal closure. 
P, posterior; M, middle; 
A, anterior spinning warts. 
L, lancet shaped chitinous 
leaf, between the two ante- 
rior spinnerets. 
i 1 cl 5 : 
Be AEs eye ee nerets; and the pair located be- 
tween these two, as the middle spinnerets.1 (See Figs. 
Orbweavers the spinnerets are short, and the anterior 
21 and 22.) With 
and posterior pairs 
1The nomenclature of these organs has become yery much confused, and I have hesi- 
tated as to what terms I should adopt, but finally haye concluded to call the six “spinning 
mammule” of Blackwall by the term which has now passed into common English use, 
namely, spinnerets; and the minute tubes upon the tips of the spinnerets, out of which the 
silk directly proceeds, by the name which they commonly receive among German writers, 
namely, spinning spools. These latter organs, Blackwall has called spinnerets, but his name 
has been transferred by naturalists and by the lexicographers to the larger organs which he 
called spinning mammule, and which the Germans generally name “spinning warts.” The 
names of the several groups of spinnerets, as determined by their relative position, are also 
much confused. I have concluded to drop the titles prevalent among German histologists 
and others, namely, inferior, intermediate, and superior, and speak of them as the anterior 
or inner, the middle, and the posterior or outer spinnerets. I also occasionally speak of 
these organs as the spinning fingers, ‘a name whose propriety has often been impressed upon 
me by their use. 
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