ON THE POISON OF ARANEIDEA. 241 
on examination to be at variance with well-ascertained 
facts, it must in like manner be deemed fanciful. 
For the purpose of testing the validity of this opi- 
nion, which I had reason to doubt, and in order to 
determine, with a nearer approximation to accuracy 
than had previously been done, some of the effects 
produced under divers circumstances by the poison of 
spiders, more especially the degree of influence it ex- 
ercises in destroying the vital functions of animals, in 
the summer of 1846 I commenced an experimental 
investigation of the subject, the particulars of which 
are comprised in the following pages. 
To avoid confusion, the experiments have been 
arranged under four distinct heads, corresponding to 
the objects upon which they were made—namely, the 
human species, spiders, insects, and inanimate sub- 
stances. It may be proper to premise that all the 
animals were adult individuals in vigorous health, and 
that the temperature of the atmosphere, in every in- 
stance recorded, was ascertained by means of a ther- 
mometer graduated according to Fahrenheit’s scale, 
and exposed to the open air in a shady situation having 
a northern aspect. 
1. Experiments on the Human Species. 
On the 19th of July, 1846, a female Epetra dia- 
dema was induced to bite me on the inner side of the 
left hand, near the base of the fore finger ; it continued 
to force its fangs deeper into the flesh during a period 
R 
