CHAPTER IT. 

 THE SPINNING ORGANS. 



The external spinning organs or spinning lingers, 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 



pinnmg ^j^^ 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 

 diviiled into pairs arranged | 

 symmetrically on either side 

 of the median line of the ^^ 

 venter, occupying a small cir- A 

 cular space immediately for- 

 ward of the anal opening. The 

 hindermost pair (nearest the ^'°;u^^;o™fete?y"separlted 

 apex), M-ill be known in this J°i ^<'^*>^y ""ignifled, bent 



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 j, ,1 fnrpinn'it niir ^- P"^"""" ^ *'• '"iddle ; 



contact. A, anterior, P, posterior, "1'""^^^^'''' ' ^"^ lOlCmOSl pail, A, anterior spinning warts. 



M, middle spinnerets. SF, spin- aS the anterior Or iuUCr Sl)in- ^' '*°<^*' shaped chitinous 



nlng field ; ac, anal closure. . ,^, . , , ,, leaf, between the two ante- 



nerets; and the pair located be- rior spinnerets, 

 tween these two, as the middle si)iimerets. ^ (See Figs. 21 and 22.) AVitli 

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



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

 tiited as to wliat torms I .should adopt, but finally have concluded to call the six "spinning 

 niannuuUc" of Blackwall by the t^'rm which lias now jia.ssed into common Knfjlish use, 

 namely, spinnorct.s ; and the minute tubes upon the tips of the siiinnerets, out of which the 

 silk ilirectly iiroceed.^, Ijy the name which they commonly receive among (ierman writers, 

 namely, siiinuing spools. These latter organs, Blackwall has called spinnerets, but his name 

 has been transferred by natimilists and by the lexicographere 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, are also 

 much confused. I have concluded to drop the titles prevalent among CTerman histologists 

 and othere, namely, inferior, intermediate, and superior, and speak of them as the anterior 

 or inner, the middle, and the jiosterior or outer spinnerets. I also occa.sionally sjieak of 

 the.se organs as the spimiiiig tingers, a name wlmsc jinipriety has iiften lieen impres.scd upon 

 me by their use. 



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