OF THE CLASS ARACHNIDA. 459 



Certain arachnida are provided with another venomous 

 apparatus destined for the same purpose, and also serving as 

 defensive weapons, such as the hook or claw which ter- 

 minates the ahdomen of scorpions (Fig. 499). This sting 

 presents underneath the point several openings which com* 

 municate with the venomous glands, and the sting of these 

 arachnida is often mortal, even to animals of considerable 

 size, as the dog. The great scorpions of hot countries are 

 also much dreaded hy man, but 

 the sting of the species inhabiting 

 Europe would seem never to be j 

 mortal; there generally arises a 

 local inflammation, more or less 

 acute, accompanied with fever and 

 stupor, sometimes vomitings and mt 

 tremblings, as the result of such 

 a wound. To overcome these 

 symptoms, medical men recom- ri s- 498 -* 



mend the use of volatile alkali, 



given internally as well as applied externally to the wound ; 

 emollient substances are also applied to the wound.f 



The intestinal canal is in general very simple, but is some- 

 times complicated, with csecal appendages which penetrate 

 even into the interior of the limbs. 



In general, tubes analogous to the biliary vessels of insects 

 open into the intestines near the anus ; but in some arach- 

 nida, such as scorpions, there exists also a liver, composed of 

 four glandular branches.^ 



It is also around the anal opening that we find the secret- 

 ing glands of the silky matter, and the winders by the aid 

 of which several arachnida construct webs, which are often of 

 great extent and of extreme fineness (Fig. 500). 



556. The respiration of the arachnida is aerian, and 

 takes place sometimes by means of tracheae ; but in most of 



* Buccal apparatus of a spider: s, the sternum; I, the lip; ma, jaws; 

 p, palpi of the jaws ; m, mandibles ; g, hooks or claws of the mandibles, 

 t In Southern Africa, and on the banks of the Great Fish River, I ob- 



. they pro 

 strong spirits. R. K. 



% These animals are numerous beyond imagination in Southern Africa, on 

 the banks of the Great Fish River. I remember a large plain covered with 

 small flat loose stones, underneath each of which there seemed to reside a 

 scorpion ; for of the hundreds turned over, we never failed to find one. They 

 were also always solitary. This was at the post of Wenzel Koosters. R. K. 



