14 Linnean Society. [Dec. 19, 1S4S. 



most powerful British spiders, even -u-hea inflicted at a moment of 

 extreme irritation and in hot sultry weather, the pain occasioned by- 

 it beino- little if any more than is due to the laceration and com- 

 pression which the injured part has sustained. 



Under the second head, the observations were made on a male 

 and female of Tegenaria chilis ; on two females of Segestria senocu- 

 lata; twice on females of Cinifio atrox and females oi Lycosa agretica ; 

 on a female Epe'ira Diadema and a female Ccelotes saxatilis ; on two 

 females oi Epe'ira Diadema ; and lastly on a female of Epe'ira Diadema, 

 which in a state of high exasperation bit itself. Extensive mechani- 

 cal injuries, Mr. Blackwall states, commonly prove fatal to spiders, 

 whether received in conflicts with their congeners or otherwise ; but 

 no e^•idence supplied by his experiments indicates that the fluid 

 emitted from the orifice in the fangs of the Araneidea possesses a 

 property destructive to the existence of animals of that order when 

 transmitted into a recent wound. 



Thirdly, as the result of numerous experiments on insects, made 

 with jEjaeira Diadema, Segestria senoculata, Epei'ra quadrata, Tegenaria 

 civilis, and Agelena labyrinthica, the author comes to the conclusion 

 that they do not present any facts which appear to sanction the 

 opinion that insects are deprived of life with much greater celerity 

 when pierced by the fangs of spiders than when lacerated mechani- 

 callv to an equal extent by other means. It is true however that 

 the catastrophe is greatly accelerated if the spiders maintain a pro- 

 tracted hold of their victims, but this is obviously attributable to the 

 extraction of their fluids, which are transfen-ed by often-repeated 

 acts of deglutition into the stomachs of their adversaries. 



Fourthly, in his experiments on inanimate substances, Mr. Black- 

 wall found that litmus- paper presented to spiders belonging to several 

 genera when in a state of extreme irritation, and moistened by the 

 transparent fluid which issues under such circumstances from the 

 fissure near the extremity of their fangs, invariably became red as 

 far as the fluid spread, clearly proving that this secretion, although 

 tasteless, is an acid. On the other hand, the fluid which flows from 

 the mouth, as also that contained in the stomach and that which is 

 discharged from wounds inflicted on the body or limbs, were found 

 by the same chemical test to be alkaline. Turmeric paper, on the 

 contran-, was rendered brown by the application of the fluids from 

 the mouth and stomach, and restored to its original colour by the 

 agency of the fluid secreted by the so-called poison-gland, thus 

 aflfording complete confirmation of the respectively alkaline and acid 

 natures of these several secretions. 



