222 
Psyche 
[September 
functions in forcing venom through the sting shaft in stinging species 
(Va, Fig. 2, D), is lacking in C. pennsylvanicus. 
Each of the two quadrate plates (QP, Fig. i, D) is anatomically 
similar to those found in most stinging Hymenoptera (Fig. i, A). 
The distal region of each quadrate plate acts as a point of insertion 
for a muscle originating on the anterior and posterior regions of 
the oblong plate. The quadrate plate articulates anteroventrally with 
the dorsal apodeme of the triangular plate (TP). 
Neither fulcral (FA, Fig. i, A) arms nor a furcula (Fu) were 
found in this species. Both the fulcral arms and furcula articulate 
with the anterior end and anteroventral region of the sting bulb 
(SB, Fig. i, A) in stinging species. Since the sting bulb is wanting, 
at least 4 muscle groups that normally insert or have their origin on 
it are also wanting. In stinging forms, these muscles typically serve 
to deflect and rotate the sting, and pass over the poison canal to 
function as a sphincter in closing the passage through which venom 
issues during the act of stinging. 
The spiracular plates (8th hemitergites, SP, Fig. 2, F) are basically 
the same as those in other hymenopterans (Fig. 1, A). Since the 
general shape of these structures changes considerably throughout the 
Hymenoptera, it is difficult to discuss any significant differences be- 
tween this and other species at this point. 
Aside from formic acid, which constitutes nearly 50% of the 
volume of the poison gland secretion (Ghent 1961), the venom 
contains one other obvious constituent, a. non-volatile residue. The 
existence of this water-soluble powder was noted by Ghent (1961), 
who estimated that it represented about 5% of the whole venom. 
The residue does not have any pronounced odor and is relatively 
insoluble in organic solvents, especially those that are non-polar. A 
clue to the identities of at least some of the components in the residue 
was obtained after it was observed that the powdery deposit reacted 
intensely with ninhydrin. After analysis by two-dimensional chroma- 
tography, it became evident that the venom of C. pennsylvanicus con- 
tains a large series of free amino acids. 
Thirteen amino acids were detected in the poison gland secretion. 
Based on the intensities of the colored ninhydrin-complexes, leucine, 
valine and serine appeared to be present in the highest concentrations. 
Lysine, proline, alanine, glutamine and x-aminobutyric acid were 
present in lower concentrations. Cystine, glycine, arginine, aspartic 
acid and threonine were minor constituents. A small amount of 
ninhydrin-positive material remained at the origin. 
