2o8 VENOMOUS ANIMALS : PROTOZOA TO ARTHROPODA 



of the scorpion are: i. Small three- jointed chelicerae, which are used 



for holding prey. 2. Large six-jointed pedipalpi, which are used 

 for seizing prey. 3-6. Four pairs of seven- jointed walking legs. 



Scorpions seize their prey with the pedipalpi, hold them close to 

 the mouth by means of the chelicer^, and sting them, if necessary, 

 by bringing the metasoma forwards over the mesosoma and cephalo- 

 thorax, and inserting the tip of the telson well into the animal's 

 body, and allowing it to remain there until the poison has had time 

 to act. The telson consists of two portions — a broad swollen part 

 (the ampulla) and a narrow portion (the spine), near the extremity 

 of which are two small openings for the escape of the venom.- 



The two poison glands lie 

 inside the ampulla, one on 

 each side of the middle line. 

 Each gland is covered with 

 a sheet of muscle on its 

 miesial and dorsal aspects. 

 This muscle, which is called 

 by Wilson ' the compressor,' 

 is inserted by its edge 

 mesially along the ventral 

 inner surface of the wall of 

 the telson, and by a broader 

 insertion laterally. The 

 compressor muscle squeezes 

 the poison out of the gland, 

 along the duct, and through 

 the opening in the spine into 

 the victim. The epithelium 

 of the gland shows three 

 distinct types of cells — -the 

 mucous cell, the fine oxy- 

 phile granular cell, and the 

 cell with very large granules. 

 Fig. 17. — Heteromeirus indus (Beer). The Venom. — Scorpion- 



(A scorpion commonly found in Ceylon.)] venom is a clear, faintly 



acid fluid of a somewhat 

 thick or oily consistence, and possessed of an extremely faint 

 yellowish colour. It contains no structural elements, but crystals 

 form in it if evaporation takes place. On an average it contains 

 about 28 per cent, of solids. 



Wilson gives the following figures for the venom of Buthus qvtin- 

 questriatus : — 



Specific gravity . . . . . . . . , . 1092 



Solids . , . . . . . , . . , . 20'3 per cent. 



Ash . , 8-4 



Proteids form part of the solids, and it is believed that the active 

 principle is either a nucleo-proteid, acid albumin, or a primary pro- 

 teose. The effects described by various authors would, however, 



