38 THE ARGENTINE ANT. 



LIFE HISTORY. 

 THE EGG. 



(PI. IV, A.) 



The egg is elliptical, pearly white, lustrous, without markings, and 

 the membrane is extremely thin and delicate. The surface is some- 

 what mucilaginous, so that wlien eggs come in contact they adhere 

 to each other. This enables the workei-s to handle them en masse and 

 also permits of their being deposited upon the walls or ceilings of the 

 ants' habitations. 



The average size is 0.3 mm. long by 0.2 mm. wide. The largest egg 

 encountered whUe measuring a series was 0.34 mm. long by 0.24 mm. 

 wide, and the smallest 0.27 mm. by 0.187 mm. 



As time for hatching approaches the luster fades and the surface 

 takes on a dull appearance. This is not sufficiently pronoiuiced and 

 uniform, however, to be taken as a safe guide to immediate hatching. 

 Wlien the embryo takes on the larval shape the membrane not infre- 

 quently adapts itself in a way to the general contour of the inclosed 

 embryo, thus making it very difficult to distinguish between the eggs 

 and the newly-hatched larvae. 



In the large Janet style cages the workei-s seem to take elaborate care 

 of the eggs in order to secure for them just the requisite amount of 

 humidity. Frequently they will be shifted several times in the course 

 of the day, first being stored in one corner, then moved to the center 

 of the compartment, afterwards carried to another compartment, and 

 perhaps finally stuck to the glass ceUing. Sometimes the eggs are 

 separated from the larvae and pupae; at other times they will be stored 

 together in apparently hopeless confusion. 



The care of the eggs by tne workers seems essential to complete 

 embryonic development. Eggs deposited in test tubes by isolated 

 queens have gone through a jiortion of the embryonic development, 

 but we have not been successful in getting them to hatch. Tliis may 

 be due in part to the ease with which the delicate embryos are injured 

 in handling and to the fact that when placed on glass the condensing 

 moisture may retard or stop development. 



The queen aj^pears to act merely as an egg-]:)ro(lucing machine, and 

 once the egg has been de})osited she pays no furtlicr attention to it. 

 The act of oviposition has been observed several times and does not 

 occu])y more than a few seconds of time. An atten(hxnt ant appears 

 to be anxiously watching for the appearance of the egg, and it is 

 inmiediately picked up and rushed off to the nearest "egg pile," 

 sometimes before it has time to touch the floor of the nest. 



Attem])ts to get fertilize<.l queens, unattended by workers, to 

 deposit eggs and rear the resulting larvae to maturity have been 

 unsuccessful. Such queens stop laying a few days after their isola- 

 tion and seemingly pay no attention to what few eggs they do deposit. 



