1968] 
Leuthold — Crematogaster 
349 
(2) Increased deviation rate from the old pathway caused by the 
new trail. 
(3) Increased deviation rate by means of the alerting stimuli. 
(4) Direct orientation of newcomers to the food through the 
new trail. 
(5) Direct returns to the food by repeated foragers. 
(6) Tandem running, active facing of encountered ants and 
attraction to agglomerations, three properties which are in- 
creased by the alerting stimuli and the consequent general 
excitement of the colony. 
The activity of recruitment behavior decreases rapidly as soon as 
the peak of newcomer ants is reached and most of the colony has 
begun to participate in foraging. The full stream of foragers con- 
tinues to flow until either the food source is exhausted or the colony 
becomes satiated with the particular kind of food present at the 
source. 
SUMMARY 
(1) Two active patterns of recruitment to the food are performed 
by food finder ants : trail-laying directed at the colony as a 
whole, and the alerting of individual nestmates. 
(2) The sequential responses to those two recruitment stimuli are: 
a) increase of running activity in the colony by means of the 
alert stimuli; b) increase of the deviation rate from the old 
pathway as the result of both the alert stimuli and the new trail ; 
c) improved trail-following or searching on either the old path- 
way or the new trail a few seconds after the perception of the 
alerting stimuli. 
(3) Several stereotyped behavior patterns favor mass-recruitment. 
These include: a) the repeated back-and-forth passages of 
pioneer recruiters between the old running area; b) the repeated 
feeding by foragers; c) the tendency of all workers to follow 
close upon a leader ant (tandem running), to join agglomera- 
tions of ants, and to face and contact crossing ants. These 
behavioral effects are augmented by the alerting stimuli of food 
finders. 
(4) The relative importance of the components and the quantita- 
tive control of mass-foraging are discussed. 
ACKNOWLEDGEMENTS 
I gratefully thank Dr. E. O. Wilson for offering me the facilities 
of his laboratories and for his critical reading of the manuscript. I 
