OHAPTEE 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 g enera a s Acrosoma and Gasteracantha they are located at or near 



mg the middle point of the ventral part of the abdomen, forming 



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 



i . T / .1 FIG. 22. The spinnerets in 



hmdermost pair (nearest the Bitu> completely separated 



t , apex), Will be known in this and feebly magnified, bent 



FIG. 21. View of the spinnerets of back and flattened, ac, 



Argiope cophinaria, represented WOrk as the posterior Or Outer semilunar anal closure. 



closed, but the parts not quite in , ,1 f orprnn ot nflir P> P sterior; M ' middle ; 



contact. A, anterior, P, posterior, S 1 H1 DS ' l CHIOS! pair, A> anterior spinning warts. 



M, middle spinnerets. SF, spin- as the anterior or inner spin- , L ' J"? ^ 3v e * cwtinous 



ning field ; ac, anal closure. , ., . , /, leaf, between the two ante- 



nerets ; and the pair located be- nor spinnerets. 



tween these two, as the middle spinnerets. 1 (See Figs. 21 and 22.) With 

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



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

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

 mammulse" 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 la- 

 called spinning maminukc, 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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