316 Biology in America 



hand will make the "fresh water Crustacean Diaptomus in- 

 tensely negatively heliotropic. " Changes of temperature and 

 osmotic pressure may bring about similar results. 



The social life of the wasps, bees and ants has long been a 

 subject for wonder and admiration. In the busy ant hive 

 is a nest full of conundrums for the student of animal be- 

 havior, the half of which have as yet scarcely been stated. 

 The life of these social insects is seemingly so complex that 

 we are accustomed to think of it in terms of human life and 

 so we have ' * castes " of " drones ' ' 7 and * ' queens ' ' and ' ' work- 

 ers." Some of these latter are "soldiers," among whom we 

 find "scouts" and "officers," others are "nurses," still oth- 

 ers are ' * harvesters ' ' whose duty it is to fill the ' ' granaries, ' ' 

 while yet others are "slave-makers," whose duty it is to go 

 out and capture "slaves." Some ants play the part of 

 "thieves" in other ants' nests. Yet others act as "hosts" 

 entertaining other species of ants as "guests," while some 

 keep aphids which they milk as ' ' cows. ' ' Some give to other 

 ants a "shampoo," in return for which the "delighted" ant 

 yields a drop of honey, which the shampooer licks up greed- 

 ily. Ants are "brave" and fight with "ferocity," while all 

 are ' l industrious ' ' and endowed with ' * wisdom, ' ' Mark Twain 

 to the contrary notwithstanding. 



Can such "human" behavior be removed from the realm of 

 poetry and relegated to the prosaic one of purely mechanical 

 reflex ? 



One of the most remarkable periods in the life of the ant 

 is the swarming time, when the winged males and "queens" 

 perform their "nuptial" flight, rushing forth in "ecstasy" 

 from their nest to found new colonies. After this flight the 

 males die, the females pull off their wings and crawling into 

 the ground either alone or accompanied by a group of work- 

 ers, settle down to the humdrum duty of egg laying. Is such 

 behavior a response to a purely physical or chemical stimu- 

 lus? According to Loeb this "wedding flight" is a "helio- 

 tropic phenomenon presumably due to substances produced 

 in the body during this period, . . . (for) at a certain time 

 in the writer's observation toward sunset, when the sky is 

 illuminated at the horizon only the whole swarm of males 

 and females leave the nest and fly in the direction of the 

 glow ' ' 8 After removing her wings the female loses her 

 heliotropism and becomes strongly stereotropic, responding 

 to touch stimuli, for if placed in a dark box containing folds 

 of cloth, she is found snugly tucked away among the folds. 



7 This term belongs of course properly to insects, and is applied sec- 

 ondarily to man. 

 Loeb, locus citatus, p. 158. 



