EFFECTS AND USES OF SPIDER POISON. 



271 



Fig. 246. The poison gland, 

 duct, and fang of Neme- 

 sia cementaria. (After 

 Blanchard.) 



II. 



From the indications of anatomy we turn to the testimony of natural- 

 ists and other observers of the effects of spider venom. First in order of 

 vakie, for their extent and thoroughness, are the experiments of Mr. Black- 

 wall, ^ an abstract of which I present. The experi- 

 menter induced a female Epeira diademata to bite him 

 on the inside of the left hand, near the base 

 Evidence ^j ^j^^ ^^^.^ fl^ggj.^ it continued to force its 



'fangs deeper into the flesh, during a period 

 of many seconds, and at last quitted its liold volunta- 

 rily, when a little blood issued from the wound. Though 

 the spider was in a state of great excitement from pre- 

 vious irritation, Mr. Blackwall did not experience more 

 inconvenience from its bite than from a puncture made 

 near it at the same time with a fine needle. The ef- 

 fects of both injuries appeared to be very similar. 



Again, a highly exasperated female Diademata was allowed to seize 

 him on the inner side of the left fore arm near the carpus. It continued 

 for more than a minute to bury its fangs deeper into the flesh. 

 Effect of .^j^^i^ Qj^ quitting voluntarily, a little blood flowed from the wound- 

 ed part, near which a puncture was made simultaneously with 

 a fine needle. The effects of this and the preceding experiment 

 were alike. In both cases the air was sultry and the temperature as high as 

 seventy-five degrees. These two wounds were inflicted in the month of July. 



In the latter part of August, a powerful 

 and much irritated female Epeira quadrata bit 

 Mr. Blackwall on the inner side of the left 

 fore arm near the carpus. It retained its hold 

 for the space of five minutes, occasionally forc- 

 ing its fangs deeper into the flesh, and, on quit- 

 ting it voluntarily, blood issued freely from the 

 punctures. The effects of this bite did not dif- 

 fer materially from those of a wound made at 

 the same time with a needle of average size, 

 the intensity and duration of pain being very 

 similar in both instances. 



During the same mouth spiders of various 

 species were induced, under the influence of ex- 

 cited feelings, to seize a piece of clean window 



Epeira 

 Bite. 



J;^»*^=^. 



Fig. 247. The mandibles of Heutz's 

 Tarantula. ,< 2. (From nature.) 

 The bristles and teeth on the inte- 

 rior surface of the fang are shown, ^ i • i 



and the opening in the fangs through glass witli their faugs, wheu a transparent fluid, 

 which the venom exudes. ^j^-^j^ escaped f roui the small aperture near their 



extremity, was deposited upon it. The application of this fluid to the tongue 



did not produce any sensible effect upon that organ. 

 • Linn. Trans., Vol. XXI., pages 31-37. 



