CHAPTER II. 

 THE SPINNING ORGANS. 



I. 



The 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 

 Spinning ^^^^ middle point of the ventral part .of the abdomen, forming 

 Organs. ^^^ ^^^^ ^^ ^^_^^ 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 



, . , . , J. 11 FiG- 22. The spinnerets in 



hnidermost pan- (nearest the situ, completely separated 



apex), will be known in this and feebly magnified, bent 

 •I. '' hack and flattened. ac. 



Fig. 21. View of the spinnerets of 



back and flattened. ac, 



Argiope cophinaria, represented WOrk aS the pOSterior Or OUtcr semilunar anal closure, 



closed, but the parts not quite in • I xi forpmost r>air ?- Posterior ; M, middle ; 



contact. A, anterior,?, posterior, ^Pl^^^^^^^^' ^^^^ lOremOSl pail, a, anterior spinning warts. 



M, middle spinnerets. SF, spin- aS the autcrior Or illlier Sl)ill- ,^' l^l^^'f* shaped chitmous 



.„,,,, ^ leaf, between the two ante- 



mng field; ac, anal closure. ^^^^^^^g . ^^^ ^^^^ ^^^-^ Xo^^X^d. bc- vior spinnerets. 



tween these two, as the middle spinnerets.^ (See Figs. 21 and 22.) With 



Orbweavers the spinnerets are short, and the anterior and posterior pairs 



^ The nomenclature of these organs has become very much confused, and I have hesi- 

 tated as to wliat terms I should adopt, but finally have concluded to call the six "spinning 

 iiiamnudte" of Blackwall by the ti'rm which has now passed into connnon English use, 

 naiuely, spinnerets; and the minute tubes upon the tips of the spinnerets, out of which the 

 silk dircH'tly proceeds, l)y tlie 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 natin-alists and by the lexicographers to the larger organs which he 

 called spinning mammuhe, and which the Germans generally name "spinning warts." The 

 names of the several groups of spinnerets, as determined by their relative position, ai-e also 

 mu(;h confused. 1 have concluded to droj) 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 i)OHterior or outer spinnerets. I also occasionally speak of 

 these organs as the spinning fingers, a name whose propriety has often been im[)i\'ssed upon 

 me })y their .use. 



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