OHBAPTER 25 
EFFECTS AND USES OF SPIDER POISON. 
Wuar 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 
are very poisonous and their bite apt 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 haye held spiders as harm- 
less to man. 
Current 
Opinions. 
Ie 
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 
repsere one with a microscope can easily 
rons o* _ 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 
Fic, 241. View of the falces (fx) and fangs creatures affected thereby. The fangs of Ar- 
vide eaving the tecth ononesiaeare giope cophinaria are shown in Fig. 241, where 
shown in outline, and the opening (o)in they are enlarged about fifteen times. The 
aes igi ta 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, gm. One also 
sees the canal, en, which contained the duct, and the little aperture at the 
extremity, 0, from which the secretion of the gland issued. 
(268) 
