SPIDEES AND MITES. 237 



swollen oval base, which is highly polished, and a more 

 slender tip, the surface of which has a silky lustre, 

 from being covered with very fine and close-set longi- 

 tudinal grooves. This whole organ falls into the furrow 

 of the basal joint, when not in use, exactly as the blade 

 of a clasp-knife shuts into the haft ; but when the ani- 

 mal is excited, either to defend itself or to attack its 

 prey, the fang becomes stiffly erected. 



By turning the object on its axis, and examining 

 the extreme tip of the fang, we see that it is not 

 brought to a fine point, but that it has the appearance 

 of having been cut oif slant-wise just at the tip ; and 

 that it is tubular. Now this is a provision for the 

 speedy infliction of death upon the victim ; for both 

 the fang and the thick basal joint are permeated by a 

 slender membranous tube, which is the poison duct, 

 and which terminates at the open extremity of the 

 former, while at the other end it communicates with a 

 lengthened oval sac where the venom is secreted. This 

 of course we do not see here, for it is not sloughed with 

 the exuviae, but retained in the interior of the body ; 

 but in life it is a sac, extending into the oephalo-tkorax 

 — as that part of the body which carries the legs is 

 called — and covered with spiral folds produced by 

 the arrangement of the fibres of its contractile tjssue. 



"When the Spider attacks a fly, it plunges into its 

 victim the two fangs, the action of which is downwards, 

 and not from right to left, like that of the jaws of In- 

 sects. At the same instant a drop of poison is secreted 

 in each gland, which, oozing through the duct, escapes 

 from the perforated end of the fang into the wound, and 

 rapidly produces death. The fangs are then clasped 

 down, carrying the prey, which they powerfully press 



