244 
Psyche 
[September 
TRAIL-LAYING FORAGER 
FROM THE FOOD 
S = EXTREMELY STRONG 
TRAIL-LAYING 
NEWCOMER ANT AFTER 
ONE RUN OF THE FORAGER 
NEWCOMER AFTER 3 RETURN- 
RUNS OF THE FORAGER 
24 cm. 
Fig. 5. — Experimental result to exhibit the efficiency of trail establish- 
ment on a graduated side bridge. Observations were transcribed from 
dictaphone. 
not exclude the possibility that the pheromone could be dispersed 
from some other place in the lower tarsus, since this is occasionally 
bent to the substrate during trail-laying (see behavior). 
Where exactly is the trail pheromone produced? A final answer 
to this question can be given only after more extensive histological 
work. It is most probable that the tissue coating the spindle reservoir 
is the pheromone gland (pi. 19 B gl), since no other likely tissue has 
been found. A chain of large granulated cells of unknown function, 
going out from the distal part of the tibia (fig. A y) 5 does not seem 
to have any connection with the spindle. , 
Explanation of Plate 19 
Morphological aspects of the hindleg 
A. Pretarsal tendon in situ. 
ch = chorodotonal organ 
y = chain of cells of unknown function 
Ai. Tendon, opened up at the end of the metatarsus. A droplet 
of trail substance is released by pressure on the tibia. 
B. Tendon pulled out with muscle attachments 
gl apparent pheromone gland 
m = muscle tissue 
sp = spindle-shaped pheromone reservoir 
C. Tendon-spindle pulled out and stained with Sudan-black 
(empty space, probably from stretching) 
D. Stained tendon-spindle after slight lateral pressure 
E. Cross sections showing the tendon-organ (numbers corre- 
spond to A) 
te = tendon 
tr = trachea 
