32 BULLETIN OF WISCONSIN NATURAL HISTORY SOCIETY. VOL. 4, NOS. 1-2. 
It should be noticed here that the females and males never 
gave any test for acid, except in a single form (female of 
Formica) ; also that as a rule only the species of genera which 
are not provided with stings showed any considerable amount of 
acid other than that which could be attributed to acid in the 
alimentary tract or in the small acid sting gland. Cremastogaster 
may prove to be an exception, but in this case most likely some 
other acid is present. Forelius is a stingless ant and we should 
expect to find it provided with acid, but it is neutral, probably 
because of the substitution of a peculiar ethereal secretion to take 
the place of the acid (see below). Pachycondyla, one of the 
Ponerinse, although provided with a powerful sting, shows the 
presence of a considerable amount of acid. The males of no 
species secrete any acid, and as a general rule the females scarcely 
ever more than a trace. 
THE DISTINCTIVE ODORS OE SOME SPECIES. 
No one who has ever collected ants extensively can have failed 
to notice the very strong and distinctive odors possessed by many 
species. Other species also, which are not particularly odorous, 
yield peculiar scents when carefully examined. 
I. ECITON. 
All the species of this genus of ants which we have examined 
(viz: B. caecum, B. schmitti, B. sumicrasti, B. opacithorax, E. 
calif omicum, B. pilsoum) possess a strikingly similar and very 
disagreeable odor. This odor, or one barely distinguishable from 
it, is secreted in even a more marked degree by species of the 
Neuropterous genus Chrysopa. In the latter insect it was long 
ago described by Say ('59) as closely resembling human feces. 
The specimens of Bciton examined were subjected to distilla- 
tion with steam and the first few cubic centimeters of the distil- 
late collected. In this was found almost all the volatile odorous 
substance. When isolated in this manner the fecal or indoloid 
odor is even more pronounced than when the worker ants are 
crushed between the fingers. As the odor strongly suggested 
indol or some of its numerous disagreeably smelling derivatives, 
tests were made for indol by crushing some of the ants on a piece 
of plantinum foil with concentrated nitric acid, then evaporating 
to a yellow residue which turned to a yellow-brown upon the addi- 
tion of a small quantity of potassium hydroxide solution. The 
