ANNULOSA I ARACHNIDA. 263 



of their prey or for lining their abodes. For the production 

 of the web, Spiders are furnished with special glands, situated 

 at the extremity of the abdomen. The secretion of these 

 glands is a viscid fluid, which hardens rapidly on exposure to 

 air, and which is cast into its proper, thread-like shape, by 

 being passed through what are called the "spinnerets." These 

 are little conical or cylindrical organs, four or six in number, 

 situated below the extremity of the abdomen. The excretory 

 ducts of the glands open into the spinnerets, each of which 

 has its apex perforated by a great number of minute tubes, 

 through which the secretion of the glands has to pass before 

 reaching the air. Many spiders, however, do not construct 

 any web, unless it be for their own habitations, but hunt their 

 prey for themselves. 



As regards the reproductive process in the Spiders, it appears 

 certain that the act of copulation, so to speak, is performed by 



Fig. 101. Araneida. Theridion ripariutn (female). 



the males by means of the maxillary palpi, the extremities of 

 which are specially modified for this purpose. The testes are 

 abdominal, but the semen appears to be stored up in the 

 enlarged extremities of the maxillary palps, which thus per- 

 form the part of the vesiculae seminales. " The most careful 

 observations, repeated by the most attentive and experienced 

 entomologists, have led to the conviction that the ova are 

 fertilised by the alternate introduction into the vulva of the 

 appendages of the two palpi of the male. Treviranus's sup- 

 position that these acts are mere preliminary stimuli, has 

 received no confirmation, and is rejected by Duge's, Westwood, 

 and Blackwall ; and with good reason, as the detection of the 

 spermatozoa in the palpal vesicles has shown. . . . Duges 

 offers the very probable suggestion that the male himself may 

 apply the dilated cavities of the palpi to the abdominal aper- 

 ture (of the testes), and receive from the vasa deferentia the 



