ANTS AND THEIR RESEMBLANCE TO MAN 



741 



ters of small, glistening food-bodies called 

 "ambrosia" (see pictures, pages 750-754). 



Some of the small Attii, instead of 

 building their fungus-gardens on the 

 floors, suspend them from the ceiling of 

 the chambers, so that the masses of sub- 

 stratum clothed with fungus filaments 

 hang down like white velvet curtains. 

 This habit is beautifully developed in sev- 

 eral species of Trachymyrmex and My- 

 cetosoritis. One of these, Trachymyrmex 

 septentrionalis, ranges as far north as the 

 pine-barrens of New Jersey. 



None of the Attii or their larvse, so far 

 as known, can eat anything except the 

 particular kind of fungus which they cul- 

 tivate. To appreciate the advantages to 

 which these completely vegetarian ants 

 have attained in thus substituting an 

 easily controllable and abundant food- 

 supply for the scarce and precarious in- 

 sect diet of their predatory ancestors, one 

 must observe these wonderful ants in 

 Brazil or Central America, moving over 

 their long trails in interminable proces- 

 sions, defoliating whole trees and carry- 

 ing their leafy burdens like banners to 

 their huge nest craters, which often 

 spread over a quarter of an acre or more. 



The foregoing remarks show that the 

 ethnic history of ants parallels that of 

 man to the extent that these insects were 

 originally flesh-eating hunters, then shep- 

 herds of food-producing herds, and 

 finally agriculturists, and that they have 

 been compelled to pass through these 

 stages or forfeit the advantages of living 

 in populous and stationary communities. 

 It is evident, furthermore, that the social 

 needs of ants, like those of man, have 

 been even more exigent than hunger. 



SOCIAL die;titians 



The skill and success with which the 

 higher ants have thus adapted their diet 

 to the requirements of sociability con- 

 trasts markedly with the conditions in the 

 other social insects. The social wasps 

 are carnivorous, to be sure, but their 

 colonies are small and rare like those of 

 the Ponerinse, and in temperate regions 

 merely annual growths. The social bees 

 have retained the exclusively vegetarian 

 diet of their solitary ancestors, but, as 

 they have greatly specialized by restrict- 



ing this diet to nectar and pollen, they 

 have become dangerously dependent on 

 the evanescent flowers. And though 

 they have learned to construct a wonder- 

 ful system of cells for food storage, they 

 are quite unable to control the food sup- 

 ply. Finally, the termites, though com- 

 pletely vegetarian, have also become too 

 specialized by restricting their diet to 

 wood, or cellulose, a hard and innutri- 

 tious substance, which, though abundant, 

 can be assimilated only with great diffi- 

 culty. 



It is significant, therefore, that the ter- 

 mites of Africa and the Indomalayan 

 region, which form the largest and most 

 aggressive colonies, have become fungus- 

 growers. But even these have not yet 

 learned, like the Attiine ants, to grow 

 "ambrosia" for all the members of the 

 colony. The working population of the 

 nests still has to live on wood in order 

 to produce the excrement which is used 

 in the construction of the gardens. The 

 fungus itself is fed only to the young and 

 to the sexual individuals. 



It is a biological axiom that all organ- 

 isms tend to propagate so rapidly that 

 they are continually in danger of outrun- 

 ning their food supply. This danger is 

 even greater in the social or colonial than 

 in the solitary organism, because the 

 former is necessarily much hampered in 

 its movements, and if every individual of 

 which the colony consists be permitted to 

 reproduce the food supply would very 

 soon become so inadequate as seriously 

 to impair the functions of the community 

 as a whole. Hence it is not surprising 

 that all social or colonial organisms are 

 bound to restrict the reproductive func- 

 tion of their component individuals. This 

 is true even of the individual organism 

 itself regarded as a colony of cells. 



re;gulating the growth of families 



The four groups of social insects have, 

 therefore, had to face a very difficult 

 problem, and it is interesting to note that 

 they have solved it in essentially the 

 same manner as other social aggregates, 

 the cell-aggregate, or individual organism 

 included, namely, by restricting the re- 

 productive function to a very few of the 

 component individuals and by reducing 



