REACTIONS OF WHIP-TAIL SCORPION TO LIGHT 



253 



glass of water; it immediately swung about, thrust its other 

 feeler into the water, then climbed half into the dish and began 

 greedily to scoop water into its mouth with its chelicerae. Sub- 

 stituting a dish with very dilute hydrochloric acid for the water, 

 a clear-cut avoidance reaction was obtained the instant the 

 feelers came in contact with the acid. 



Centimeters. 



Fig. 1 Mastigoproctus giganteus Lucas: 1, chelicerae; 2, pedipalps; 3, modi- 

 fied anterior legs which serve as feelers; 4, 5, 6, walking legs; ?ne, median eye; 

 le, lateral eyes. 



The big pedipalps are surprisingly powerful and can inflict a 

 considerable flesh wound. A peculiar feature of the action of the 

 pedipalps is their alternate striking and grappling movement 

 which carries the attacked object forcibly toward the chelicerae. 

 Of interest in this connection is the statement of McMurrich 

 ('94, p. 446) that the chelicerae of the Thelyphonids bear the 

 outlets of poison glands on their terminal spines. Borner ('04, 

 p. 12) did not find any poison outlets in the chelicerae of the 



