1960] 
Eisner — Deferise Mechanisms 
6 3 
No sooner had a stimulus been applied than the animals responded 
by revolving their abdomen, bringing the pincers to bear upon the 
region traumatized. They usually succeeded in grasping the instru- 
ment used for stimulation ( Plate 7, figs. 2, 3) and, by pulling and 
tugging, attempted to free themselves from it. They sometimes re- 
leased their grip momentarily, but as a rule persisted tenaciously for 
as long as the stimulus was maintained. The abdomen is remarkably 
maneuverable, being capable of bending and twisting to such an 
Text Figure 1. Forficula auricularia Linn, showing the four glandular- 
openings and the cuticular sculpturing around them on the third and fourth 
abdominal tergites. 
extent that virtually no body part other than the abdomen itself is 
inaccessible to the pincers. Since the abdomen responds rapidly and 
with precision, the pincers can be shifted accurately and without delay 
from one region to another. This became quite clear when the ani- 
mals were subjected to a rapid sequence of stimuli applied to different 
parts of their body. 
The pressure that the animals can exert with the pincers is con- 
siderable. From personal experience, I can attest to the claim (cited 
by Burr, 1910) that the sharp prongs can pierce human skin (the 
prongs of the male are larger and somewhat more effective than those 
of the female) . 
The Glands 
Adult earwigs, affixed to rods as before, were again subjected to 
localized stimulation, but this time they were placed on sheets of 
filter paper impregnated with an acidulated Kl-starch solution. This 
paper discolors to an intense blue-black in the presence of quinones, 
and can therefore be used as an appropriate indicator for the detection 
of glandular discharges. 
In Plate 8 are shown the types of pattern produced by the secre- 
tion. Evidently, the gland contents do not merely ooze out, — as 
