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THE POPULAR SCIENCE MONTHLY 



ities encounter each other in the centre. Then conceive these knives 

 to have the edges of their blades serrated with a row of fine teeth com- 

 mencing near the haft, and on the handle itself five large, pointed teeth, 

 shaped like the head of a lance, and upon which the saw-like blade can 

 be brought to work to and fro." The large claw or horn (Fig. 3) an- 

 swers to the blade, a representing its fine teeth, while b shows the five 

 lance-like teeth in the handle against which the blade works. But, be- 

 sides these mandibles, the spider possesses a smaller pair of jaws, called 



Fig. 3. 



Termination of the Jaw, or Mandible. a, Eow of Teeth on the Claw ; &, Basal Joint of Mandible, showing' 

 the Five Large Teeth ; c, Commencement of Poison-sac ; d, Course of the Poison-duct. The last two 

 are only visible when the mandible has been carefully bleached with chlorine. 



the " maxillae," which also have finely-toothed edges like deeply-cut 

 rasps that most probably operate one against the other, to enlarge the 

 wound made by the mandibles. This looks formidable enough, but it 

 is not the worst. Nature has equij>ped the spider for very thorough 

 work. This combination of dirks and saws is poisoned. At the basal 

 joints of the mandibles there is a receptacle filled with a subtle ven- 

 om which is conveyed through a tube (Fig. 3, d) to the pointed ex- 

 tremity of the blade. The moment this pierces the body of the prey, 

 the poison is emitted, and, entering the wound, renders it fatal, proba- 

 bly at the same time benumbing the sensibility of the victim. The 

 injected poison is nearly colorless, and possesses most of the proper- 

 ties that exist in the venom of the rattlesnake or the viper. The bite 

 of a large spider on the back of the hand has been known to swell the 

 whole arm, so that it was hardly recognizable as belonging to the hu- 

 man figure. 



There is a famous spider called the tarantula, from the town of 

 Tarentum, in Italy, where it is plentiful. It is believed by the people 

 of that region that the bite of the tarantula produces the most ex- 



