SPIDERS. 



117 



Fig. 167. — Head 

 and mandibles of 

 JEpeira. 



in the wind, but in most cases this is certainly not done, only one thread being visible. 

 Sometimes while a thread is blown from the hinder spinnerets, another from the front 

 spinnerets is kept fast to the ground, so that when the spider blows away it draws out 

 a thread behind it entirely independent of the one from which it hangs. Some- 

 times instead of a single thread several are blown out at once, like a long brush. 



When undisturbed spiders never bite anything except insects useful for food ; but 

 when attacked and cornered all species open their jaws and bite if they can, — their 

 ability to do so depending on their size and the strength of their jaws. Notwith- 

 standing the number of stings and pimples that are laid to spiders, undoubted cases 

 of their biting the human skin are very rare ; and the stories of death, 

 insanity, and lameness from spider-bites are probably all untrue. The 

 biting apparatus is shown in Fig. 167, which repi-esents the head and 

 mandibles of JEpeira vulgaris, seen from in front. When not in use 

 the claw is closed up against the mandible between the rows of teeth ; 

 but when the jaws are opened to bite the claws arc turned outward, 

 so that their points can be stuck into anything between the jaws. 

 Fig. 168 is the claw still more enlarged, showing a little hole near 

 the point at a, out of which is discharged the secretion of the poison 

 gland. The ordinary use of the mandibles is for killing and crush- 

 ing insects so that the soft parts can be eaten by the spider, and in this they 

 are aided by the maxillte. They will sometimes chew an insect for hours, until it 



becomes a round lump of skin with all the blood sucked 

 out of it ; this is then thrown away, the spider swallowing 

 only such bits as may happen to be sucked in with the 

 liquid portion. 



Many experiments have been tried to test the effect of 

 the bites of spiders on animals. Doleschall shut up small 

 birds with Mygale jav.anica and My gale sumatrensis, both 

 large and strong spiders, and the birds died in a few 

 seconds after being bitten. The same author was bitten 

 in the finger by a jumj)ing spider. The pain was severe 

 for a few minutes, and was followed by lameness of the 

 finger, and gradually of the hand and arm, which soon 

 went away entirely. 



Bertkau allowed spiders to bite his hand. On the ends 

 of the fingers the skin was too thick, but between the fingers they easily pricked it. 

 The bite swelled and smarted for a quarter of an hour, and then itched for some 

 time, and for a day after itched whenever rubbed, as mosquito bites will. Mr. 

 Blackwall made several large ones bite his hand and arm, and at the same time 

 pricked himself with a needle. Although the spiders bit deep enough to draw blood 

 the effect of their bite was exactly like that of the prick of the needle. No inflam- 

 mation or pain followed, and both healed immediately. 



In the classification of the spiders the relative position of the eyes and the length 

 of the legs' are very important, affording both family and generic characters. The 

 shape of the web is also distinctive. 



Pig. 168. — Tip of mandible, 

 greatly enlarged, a. Outlet of 

 poison-gland. 



