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Their function is to seize and kill the prey, but they do not assist in mastication. 
Each falx is composed of two parts, the base and the fang. 
The base serves simply as the support for the cutting instrument, and has a 
groove on its under surface into which the fang is folded -down when not in use 
The fang is hard, sharp, and sickle -shaped, and is, in the instance we are con- 
sidering, armed with a row of thirty pointed teeth on each side, and a smaller 
number on the under surface. 
Attached to the fakes is a highly interesting apparatus which is believed 
materially to assist the spider in the capture of its food. 
This consists of two glands composed of a number of filaments united by a 
membrane into the form of a sac; these are situated in the interspaces of the 
muscles of the cephalo-thorax,and communicate with the falces by means of a duct. 
These glands secrete a fluid which is supposed to possess slightly poisonous 
properties, and thus to aid in the destruction of the insects on which the spider 
feeda. Stories are told of the bite of spiders having proved fatal even to man, 
these are not, however, supported by very reliable evidence. Certainly no Eng- 
lish Spider is capable of inflicting a bite sufficiently hard even to pierce the human 
skin. This I have frequently proved by experiment. * 
So far as I am aware, no experiments have been made to prove the directly poison- 
ous properties of this secretion. Any such experiments are, i n the case of our British 
Spiders, surrounded with great difficulties ; speaking for myself I may say that 
some I have made in reference to this question have been only in a measure satis- 
factory, but such as they were, they rather tended to show that this fluid did 
possess some properties fatal to insect life. 
The exact position of the orifice in the fang through which this fluid exudes, 
has long been a question of dispute. 
Very recently a discussion took place in the pages of one of our Scientific 
Journals on this point. Some of the disputants even went so far as to deny the 
exist ence of the glands altogether ; but this would appear to have been the result 
of faulty dissection. The dispute was closed by a communication from the late 
Mr. R. Beck, illustrated by a drawing, in which he showed the orifice as being 
on the side of the fang near the point, in this following Leeuwenhoek and some 
other Arachnologists. 
After a very careful examination of many of these fangs, I have come to the 
conclusion that the appearance believed by Mr. Beck to indicate the position of 
the orifice really arises simply from the peculiar arrangement of certain striations 
on the fang. Of course the assigning of the position of a minute orifice on a fang, 
itself about the l-50th of an inch in length, is a matter of no small difficulty. 
The celebrated Cuvier, and many modern foreign Arachnologists, place this 
orifice on the under surface of the fang near the point, a position on many 
grounds much more likely for the exit of the duct than that on the side. This 
position, from what observations I have made on our British Spiders, and also on 
an example of a large foreign "Bird Spider," I am led to believe to be undoubtedly 
the true one. 
The food which has been captured and killed by the falces is next conveyed to 
the mouth. This consists externally of an upper and under lip, and a pair of 
maxillae or jaws. 
The upper lip can only be detected externally by its hairy tip, which is in reality 
merely the termination of the palate. 
