JUAN FINAS— AROUND THE LAGUNA 179 



composite with heads two inches in diameter. The blossoms 

 of the Isoloma were attractive to the large black and yellow 

 swallow-tail butterfly Papilio thoas, whose wings at this 

 time were much torn. Both in December and February 

 we found a species of Siphocampylus blooming on the rail- 

 road banks, where also grew an odd little Urticaceous plant 

 {Pilea microphylla) and a handsome small poke {Phyto- 

 lacca decandra) with bright purple flowers. Among the 

 cinders of the roadbed were small Euphorbs {Euphorbia 

 nutans). 



Nests and paths of the leaf-cutter or "parasol" ants {Atta) 

 were common about the laguna and railroad. These insects 

 derive their English names from the habit of cutting bits 

 from leaves or other parts of plants and carrying them in 

 their jaws, balanced over their heads or bodies, to their 

 underground nests. Thomas Belt, during his four years' 

 stay in Nicaragua, and independently Fritz Miiller in Brazil, 

 ascertained that on these leaf-fragments in the nests grows a 

 fungus, which is used by the ants as food; the leaf-fragments 

 themselves are subsequently abandoned as refuse. Alfred 

 Moeller, working in Brazil, found that the parts of the 

 fungus used by the ants are pale white corpuscles, .25 to i 

 mm. in diameter, which he called " kohl-rabi clusters " and 

 which, he believed, are due to culture by the ants, as they 

 are not formed when the fungus is experimentally grown 

 apart from the influence of the ants. 



On some firmer ground on the west side of the laguna was 

 quite a large nest with many openings and well-defined and 

 hard-trodden ant paths leading to it. On October i we 

 found ants {Atta cephalotes) carrying pellets of refuse material 

 out of several of the openings but very few, almost no, ants 

 carrying leaves or other burdens into the nest. Among the 

 ejecta was an Aphodiid beetle {Atcenius strigicauda) 5 mm. 

 long, shining blackish, although the strongly knobbed antennas 



