112 
Psyche 
[December 
The spectra indicated the presence in the crude extract 
of an ester (the principal compound) and a fatty acid. An 
attempt was made to separate the fatty acid from the mix- 
ture. The solvent of the original solution was evapor- 
ated and the residue dissolved in ether which was then 
washed with dilute Na 2 C0 3 . The alkaline wash containing 
the sodium salt of the fatty acid was separated from the 
ether solution containing the ester. The infrared spectrum 
of the ether solution compared well with the original crude 
material, indicating that the ester had been removed. The 
alkaline wash containing the Na salt of the fatty acid was 
acidified with dilute HC1 and extracted with ether. The 
infrared spectrum of this ether extract indicated a fatty 
acid though the spectrum was not sufficiently distinctive 
to identify the compound specifically. In a series of tests 
using treated and untreated (control) paper squares, it 
was found that both the fatty acid and the ester evoked 
the necrophoric response. However, the fatty acid appeared 
to be the more effective of the two, in that it tended to 
release the response more quickly and to induce transport 
of the treated squares over greater distances. It was further 
observed that the acid-daubed squares were as a rule trans- 
ported further away from the nest entrance during initial 
transport. Also, the ester-daubed squares frequently caused 
an initial mild alarm reaction that delayed the necrophoric 
response even more, whereas the acid-daubed squares were 
never observed to do so. It is possible that complete sep- 
aration of the acid and ester was not obtained and that 
contamination of the ester fraction with the acid could 
account for the equivocal results. 
Use of another test species. An attempt was next made 
to determine whether the fatty acid obtained from Pogon- 
omyrmex barbatus would release necrophoric behavior in a 
phylogenetically remote ant species, Solenopsis saevissima 
(Fr. Smith). Four paper squares daubed with the acid were 
inserted, along with four control squares, into the brood 
chamber of an artificial nest containing a colony of S. 
saevissima. Within 25 minutes all four of the treated 
squares had been carried out and placed at the edge of 
the nest. Soon afterward the control squares were brought 
