2 i8 POISON- APPARATUS, AND DIGESTIVE SYSTEM. 



816. Certain of the Arachnida are provided with another 

 poison apparatus, destined for the same use, and serving equally 

 as a weapon of defence : such is the hook by which the abdomen 

 of Scorpions is terminated (Fig. 554). This sting has beneath 

 its point several openings, which communicate with a poison- 

 gland ; and the sting of these Arachnida often proves mortal, 

 even to animals as large as Dogs. The large Scorpions of warm 

 countries are fatal even to Man, but the sting of the species 

 which inhabit Europe never appears to be m *tal ; there usually 

 results from it a local inflammation more or less violent, accom- 

 panied by fever and depression, and sometimes by vomiting, 

 pains in the whole body, and trembling. To overcome these 

 attacks, physicians advise the use of ammonia (or spirit of harts- 

 horn), administered internally as well as externally ; and the 

 application of emollient substances to the wound. 



817. The intestinal canal is generally very simple ; but has 

 sometimes csecal appendages, which penetrate even into the 

 interior of the limbs. In general, tubes analogous tothewrinary 



po ab po t 



Fio. 546. ANATOMY OF MYOALE : ct, cephalothorax opened below, and giving attach- 

 ment to the limbs, whose first joints are exhibited ; pa, legs of the 1st pair ; p, palpi ; 

 m, mandibles ; afe, abdomen ; t, thoracic nervous mass ; a, abdominal ganglia ; po, 

 respiratory sacs ; t, stigmata ; I, leaf-like folds in the interior of one of these laid 

 open ; ov, ovaria ; or, orifice of oviducts ; ma, muscles of the abdomen ; an, anus ; 

 /, spinnerets. 



vessels of insects open into the intestine near the anus; but 

 amongst some of the Arachnida, such as the Scorpions, there 

 exists a liver composed of four glandular clusters. It is also in 



