30 
Psyche 
[March 
Table 2. Response of Paratrechina longicornis workers to artificial 
trails prepared from four abdominal organs. 
No. of 
No. of workers 
Organ 
replications 
responding 
Poison gland 
8 
0,0, 0,0, 0,0, 0,1 
(plus vesicle) 
Accessory gland 
8 
all 0 
Hind gut 
8 
0,4,8,8,11,15, 
Ovary 
8 
3 T 37 + 
all 0 
Control (water) 
8 
all 0 
Duration of 
response to 
nearest % min. 
V2 
2 , 7 ^ 4,20 + 
side product of digestion or as a special secretion of the gut wall. 
Examination of the freshly dissected gut wall under low power with 
a light microscope failed to reveal obvious glandular tissue that 
could serve as a possible source. But this is in itself quite incon- 
clusive, since inconspicuous unicellular glands are known to abound 
elsewhere in the ant body. Also, the data do not reveal whether the 
trail substance is actually manufactured in the hind gut, or whether 
it is produced forward of the hind gut and passed — perhaps in 
precursor form — back with the gut contents. The solution of these 
questions awaits the development of a finer dissection technique than 
the one used in the present study. 
These preliminary results have an important phylogenetic implica- 
tion. All seven non-formicine genera on which similar experiments 
have been conducted ( Solenopsis , Pheidole , Tetramoriurn, Acro- 
myrmex, A tta, Iridomyrmex , Monads; see Wilson, 1963) secrete trail 
substances from glands not associated with the hind gut. Moreover, 
the two formicine species reported here belong to widely different 
branches of the subfamily: Myrmelachista constitutes a tribe by itself 
within Emery’s section Alloformicinae, while Paratrechina is a mem- 
ber of the tribe Lasiini of the section Euformicinae. No member of 
the third formicine section, the Heteroformicinae (consisting of the 
tribes Myrmecorhynchini and Myrmoteratini) has been investigated. 
It will be of interest to see whether trail-laying species in other 
formicine genera and tribes also use the hind gut as a primary source. 
Literature Cited 
Carthy, J. D. 
1951. The orientation of two allied species of British ant. II. Odour 
trail laying and following in Acanthomyops (Lasius) fuliginosus. 
Behaviour, 3:304-318. 
