HOW SANGUINARY ANTS CHANGE AT WILL THE 



DIRECTION OF COLUMN IN THEIR FORAYS 



(F. SAX GUINEA VAR.). 



By A. C. Burrill. 



For several years, I have been interested in the habits of 

 our American Sanguinary or Slave-making ant, especially the 

 variety Formica sanguined rubicunda var. subintegra, 1 watching 

 forays of certain nests for several consecutive summers. I have 

 not failed to note the great variability in trail-following by these 

 sanguinaries, in marked contrast, for example, to Cremastogaster 

 lineolata Say, which follows the minute sinuosities of a zig-zag 

 ground trail with a slavish zeal that would seem to betray com- 

 plete dependence on scent to the decadence of sight or of a gen- 

 eral sense of direction. Individuals or even squads of Sanguin- 

 aries have been seen to leave a well-travelled trail at right angles 

 to investigate some side attractions independent of the goal of 

 the expedition. 



It is still more interesting to find that, approximately three 

 times out of fifty or more expeditions, the whole expedition may 

 change its course, apparently about as quickly and as markedly as 

 the individual. 2 The fact that ants change their course at will 

 presents to my mind one of the most serious difficulties which we 

 have to contend with in coming to a complete understanding of 

 what is called direction through scent as the chief guiding sense, 

 and to the adoption of this theory as a working principle in the 

 psychological study of ants generally. It appears to indicate that 

 the sense of smell may be superseded any moment by that of sight 

 or by the individual's will to fluctuate in its adherence to scent. It 

 appears in Sanguined that the sight of the many or some social 

 responsiveness of the man}- ( a responsiveness considered usually 



1) Identified through the kindness of Prof. W. M. Wheeler, Feb. 1908; 

 but raised to subspecific rank in Wheeler's "Ants," 1910, p. 570, F. sang. sub- 

 Integra. 



2) Sir John Lubbock has already noted that a neuter ant will seek to 

 straighten out many unnecessary kinks and curves in the trail. Ants, Bees & 

 Wasps. 1901 ed. D. Appleton & Co. N. T. pp. 270-1. 



123 



