OHAPTEE XVI. 



EFFECTS AND USES OF SPIDER POISON. 



WHAT are the effects of spider venom? Nothing connected with the 

 life history of spiders has given rise to greater diversity of opinion than 



this question. The well nigh universal belief is that all spiders 

 Current . -, ., , . , 



Opinions are verv P olsonous and tneir "ite a pt to be serious and even 

 ' fatal to human beings. It is this, doubtless, which maintains 

 the most unjust popular dread of and hostility to these useful animals. 

 On the other hand, naturalists have been generally inclined to an opin- 

 ion quite the reverse of the popular one, and have held spiders as harm- 

 less to man. 



I. 



Let us first inquire what light anatomy can throw upon the subject. 

 More than two hundred years ago Leeuwenhoek gave a substantially cor- 

 rect description of the fang of a spider, pointing out the small aperture 



through which the liquid poison is emitted. 

 Since that time the poison apparatus has 

 been frequently described, and any 

 ica- one w i^ n a microscope can easily 



satisfy himself of the facts. What- 

 Anatomy. 



ever may be the effect of the secre- 

 tion from the poison glands of spiders, it is 

 certain that the organs and armature secret- 

 ing and conveying the venom are formida- 

 ble enough to suggest the idea of injury to 

 FIG. 241. view of the faices (fx) and fangs creatures affected thereby. The fangs of Ar- 



of Argiope cophinaria, from camera lu- -, . . , -,-,. c\A-t i 



cida drawing. The teeth on one side are giope cophinaria are shown in Fig. 241, where 

 shown in outline, and the opening (o) in they are enlarged about fifteen times. The 



the fang is shown. X 15. j-i-i r i i .1 i j 



mandibles from which the drawing was made 



were taken from a nearly adult female. The falx, fx, was about two mil- 

 limetres long and one millimetre wide. The fang itself was about one 

 millimetre in length. When examined under the microscope it showed 

 very clearly the matrix in which the poison gland had been placed, as 

 seen in the outline drawing (camera lucida) at Fig. 242, g.m. One also 

 sees the canal, en, which contained the duct, and the little aperture at the 

 extremity, o, from which the secretion of the gland issued. 



(268) 



