20 



Dr. A. G. Bourne. 



[Jan. 13, 



4. After considerable search I procured some specimens of Thely- 

 plwnus, which I chose as being the nearest relatives of the scorpions. 

 I stung these in my usual method, and in each case they died within 

 six seconds. I then tried some spiders ; they died in a few minntes 

 when well stung. The action on cockroaches and crickets is described 

 above. The equally rapid local but slower general action in these 

 latter animals is probably to be explained by the very inefficient 

 circulation of the blood in insects as compared with Arachnida. It 

 would be an interesting experiment to sting a Limulus, and compare 

 the effect with that on a crustacean, and with that on other Arachnida. 



5. While keeping a quantity of scorpions together in captivity it is 

 not difficult to induce a couple to fight. I isolated such a couple, and 

 they fought on and off for two days, duriug which time each repeatedly 

 stung the other. The scorpions face one another, and the more 

 powerful manages to hold the other's chelae within its own with a 

 sort of hugging action ; it then fights with its cheliceree, clawing 

 about the region of the mouth. A strong scorpion will actually tear 

 out the chelicera of a small one in this manner ; it then proceeds to 

 suck the blood and juices. 



On another occasion I separated from one another two scorpions 

 which had been fighting, and which had repeatedly stung one another. 

 They lived perfectly well. 



6. Apropos of Mr. Gillman's remarks about the actual temperature 

 to which the scorpion is subjected in the " fiery circle," I tried this 

 experiment. I placed a scorpion and a cockroach (for comparison) in 

 an incubator with glass sides ; I gave them a piece of wood to walk 

 about upon, and gradually raised the temperature. At 40° C. both 

 seemed uncomfortable, the cockroach performed a sort of licking* 

 action on all its legs and antennas ; at 45° C. the scorpion became 

 very sluggish, and at 50° C. it was nearly dead. A large furious 

 scorpion before the experiment, it now lay on its back and did not 

 attempt to get up. I took ifc out and gave it a cold bath, and put 

 it in a cool earthenware vessel, and it gradually (two hours) 

 recovered. The cockroach I left in the incubator till the temperature 

 reached 52° C. ; when it was nearly dead I took it out, and it very 

 gradually recovered. 



To try the effect of a wet heat I placed a scorpion and a cockroach 

 in water at 43° C, and they both died almost immediately, whereas 

 they would both have lived in cold water for hours. 



In conclusion, I think we can understand how various observers 

 have been led to form conflicting opinions, but I think we may safely 

 assert that scorpions do not commit suicide. There is not only an 

 absence of proof that they possess any instinct to do so, but absolute 

 proof that it is chemically impossible for them to do so — at any rate, 

 in the species which I have examined. The immunity of the scorpion 



