34 



BULLETIN OF WISCONSIN NATURAL HISTORY SOCIETY. VOL. 4, NOS. 1-3. 



These ants are very small and cannot be conveniently picked 

 up by the forceps, but may be collected in almost any number by 

 placing pieces of filter paper soaked in sugar solution near the 

 nests. They collect on the paper to feed upon the sugar and may 

 be easily shaken into a bottle. 



When distilled with steam the odor passes over and remains 

 dissolved in the aqueous distillate. Thus freed it retams the very 

 evident odor of rancid cocoanuts. By saponification ^vlth potas- 

 sium hvdroxide solution it loses all odor, but on adding dilute 

 sulphuric acid to excess an odor closely resembling that of fresh 

 cocoanuts is developed. From this it is quite evident that the 

 odorous principle is an ether of some sort. Attempts to identify 

 the free acid were not successful; its odor is too pleasant to 

 associate with any of the lower straight chain fatty acids but may 

 possibly be due to a forked chain one, or to a higher fatty acid. 

 It does not seem likely that it is an aromatic acid. 



in. CAMPONOTUS MACULATUS, VAR SANSABEANUS. 



All the castes of this ant, and more especially the males, 

 possess a strong, sweet pelargonic smell which very closely re- 

 sembles a bouquet of valerianic and butyric ethers. The odor is 

 at first concealed by the stronger smell of formic acid, but is very 

 pronounced when an aqueous distillate from the ants has been 

 neutralized with an alkali. This physiological peculiarity readily 

 serves to separate it from Camponotiis fumidus, an allied form 

 which often greatlv resembles it in the worker major caste for 

 the latter species is' wholly devoid of the geranium-like odor. 



IV. FORMICA FUSCA VAR. GNAVA. 



This ant, too, has its own distinctive odor, which can be readily 

 recognized after the aqueous distillate has been neutralized with 

 an alkali. The odor is exactly that of the mixture of sodium 

 palmitate and oleate, which give to ordinary soap its odor. 



v. CRFMASTOGASTER UNEOLATA, VAR. CLARA. 



The odor associated with this ant is one of the most unpleasant 

 that we have encountered in the course of our work. At first the 

 fresh ants have quite a strong odor strikingly similar to chlonne. 



*We are thus enabled to repeat on a small scale in the animal 

 kingdom, the physiological separation of species by olfactory means, 

 a thiB^r which ha^ often been effected by botanists with plant species, 

 more notably among the roses (cf. Kerner and Oliver, 95). 



