The Life of Spiders 



The structure of the hackled bands differs in different fami- 

 lies; and sometimes, in different genera of the same family. But 

 in all that I have examined, the band consists of two elements: 

 first, two or more longitudinal strands, the supporting part of 

 the band, this may be termed the warp; and second, a viscid, 

 sheet-like portion, supported by the warp, this may be termed 

 the woof. 



The warp in the hackled band of Uloborus and of Hyptiotes 

 (Fig. 236) consists of two, straight, parallel threads; in that of 

 Dictyna of a pair of greatly curled threads; and in the band of 

 Amaurobius (Fig. 250) of two straight threads and two greatly 

 curled ones. In Filistata there are a supporting double thread 

 and two pairs of curled threads differing greatly in size and 

 arrangement (Fig. 285). 



In most cases the woof is an amorphous sheet; but in the 

 bands of Uloborus and of Hyptiotes it consists of a series of regular, 

 overlapping lobes. 



Very little is known regarding the source of the two or 

 more kinds of silk that are used in forming a hackled band. 

 The size of the threads forming the warp indicates that they 

 are spun from spigots; and it seems probable that the woof is 

 derived from the cribellum; but I have been unable to verify 

 these conjectures. 



The method of making a hackled band is also not well under- 

 stood. It is easy to see that the spider in doing it places the 

 calamistrum of one hind leg beneath the spinnerets and makes 

 a rapid combing motion. It is probable that the lobed nature 

 of the warp of Uloborus and of Hyptiotes is produced in this way; 

 but is the amorphous sheet that forms the woof of other genera 

 thus formed? If so, how are the curled threads of the warp 

 given their characteristic form? 



The silk of the egg-sacs. — The silk of the egg-sac of many 

 spiders presents an appreciably different appearance than does 

 other silk spun by the same spiders. According to Apstein 

 ('89) this silk is produced by the cylindrical glands of the female. 

 These, in the forms studied by this writer, are six in number and 

 open by spigots, one on each of the middle spinnerets and two 

 on each of the hind ones. These glands are said to occur as a 

 rule only in females and to be wanting in the Attidae and in 

 the Dysderidae. 



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