374 



AXTS. 



spicuously fond of feeding on the saccharine excrement of aphids and 

 coccids, have themselves developed a capacity for distilling a substance 

 resembling honey-dew. 



In the foregoing pages the habit of developing repletes has been 

 shown to recur sporadically in at least six different genera of ants, 

 namely, Prcnolcpis, Mclnphonts, Plagiolcpis, Lcptoinvnnc.r, Campo- 

 notiis and M ynnecocystns. We are therefore dealing with a case of 

 convergent development and as in other cases of this kind, we are 

 led to determine the external conditions that act as the common 



FIG. 221. Replete Myrmecocystits horti-deorum in the act of regurgitating food to 

 workers of the ordinary form. (McCook.) 



stimulus in calling forth this peculiar adaptation. The geographical 

 distribution of the various honey ants seems to point to drought as 

 one of the most important of these conditions, for nearly all of 

 these insects are confined to the dry plains and deserts of North 

 America, South Africa and Australia. Forel seems to be the only 

 author who has noticed this peculiarity in the distribution of the honey 

 ants. He says (1902^): "The extraordinary distension of the crop 

 seems to be frequent in the Australian species of the genera Melo- 

 phonts, Camponotus and Leptomynnex. I suppose that this is due to 

 the extremely dry climate of the country, which must compel the ants 

 to remain, often for long periods, in their subterranean abodes. At 

 such times a store of provisions in living bags must be very useful to 

 them." 



There can be little doubt of the truth of this statement, but I believe 

 that it should be expressed in a different manner. The impulse to 

 develop repletes is probably due to the brief and temporary abundance 

 of liquid food (honey-dew, gall secretions, etc.) in arid regions and the 



