2l8 
Psyche 
[September 
be elaborated by Dufour’s gland and ultimately mixed with the 
poison gland secretion. The venom produced by the poison glands 
of formicine ants has long been identified with formic acid, and it 
is quite clear that this compound is a consistent chemical denominator 
for the venomous secretions produced by members of the Formicinae. 
However, arthropod secretions usually have many components, and 
formicine venoms do not appear to violate this generalization. Thus, 
Stumper (1959) has demonstrated that the venom of Formica 
polyctena Forster contains in addition to formic acid, at least two 
other minor constituents. Similarly, Ghent (1961) reported that 
the venom of Camponotus pennsylvanicus (DeGeer) was character- 
ized by the presence of a water-soluble solid which constituted about 
5% of the venom. 
This research is part of a comparative study of the hymenopterous 
poison apparatus. An investigation of other formicine species is 
presently underway and will be reported on in forthcoming publica- 
tions. 
RESULTS 
The poison sac (PS) differs from the sacs of ants in other sub- 
families in that there is no gland invaginated into the sac (Fig. 2, 
A, B). Instead, an extremely long and narrow convoluted duct 
(CG) lies adnate to the dorsal surface of the sac. This duct 
branches into two long free filaments (FF) at the base of the sac. 
These filaments maintain a relatively uniform diameter throughout 
their length. 
The basic composition of the reservoir, convoluted duct and free 
filaments is the same in this species as in other formicids previously 
described (Forel 1878, Maschwitz 1964). The difference lies in 
the position of the convoluted region. In most formicids, the con- 
voluted portion, responsible for enzymatic activity in changing pre- 
cursory compounds picked up by the free filaments, is totally within 
the sac (unpublished data). In C. pennsylvanicus , this region lies 
on the outside of the sac, and by pulling on the base of the free 
filaments, the elongate convoluted duct can be unraveled. 
Fig. 1. Comparison between the poison apparatus of Camponotus penn- 
sylvanicus and what may be considered a typical stinging ant. A-Apparatus 
similar to that found in ponerine ants (LV). B-Transverse section through 
sting of a stinging ant species. C-Distal tip of sting showing barbed lancet 
tips extending posteriad from tip of sting shaft (LV). D-Poison apparatus 
of C. pennsylvanicus (LV). 
