268 NATURAL SCIENCE. Oct., 



spots, becomes finer, closer, and more regular. Indeed, in comparison 

 with the rest of the surface, the stridulating area looks smooth, and a 

 high power and appropriate light are required to make the lines 

 apparent. In the Myrmicides, the lines appear to be not always 

 mere modifications of the general sculpture ; in some cases they are 

 described as being " developed on a glassy surface poured out on the 

 ordinary surface." In a species of Sima from Australia, the area 

 was found to be divided into two parts, the lines on the one part 

 being much coarser than those on the other, and doubtless enabling 

 the insect to modify the sound produced. 



The delicate instrument formed by the fine sculpture is played 

 upon by the specially modified hinder margin of the segment in front, 

 which projects downwards to form a very sharp and even edge. This, 

 drawn across the fine ridges, as the ant moves her abdominal 

 segments, must give rise to an excessively high note. In some cases, 

 at least, the sound is audible to human ears. By moving the appro- 

 priate parts, Dr. Sharp has produced sounds with species of leaf- 

 cutting ants (Atta). Mr. Wroughton (3) has described the action of a 

 colony of Indian ants (Crematogaster) when disturbed ; they wag their 

 abdomens, and emit a sound " as if a red hot cinder had been plunged 

 into water." The Camponotides, to which most of our common 

 British species of ants belong, do not appear to possess stridulating 

 organs. 



Leaf-cutting ants are familiar to readers of books of tropical 

 travel, and the object of the insects in collecting leaves has been 

 differently explained by various observers. The opinion advocated 

 by Belt, that the ants tear up the leaves in order to make beds on 

 which a crop of fungi may be grown, was confirmed by Mr. Cook, 

 and has recently received more detailed confirmation from the 

 researches of Herr M oiler (4), who has studied the habits of these 

 ants in Brazil. Within their nest is a soft, spongy mass, consisting 

 of the remains of leaves, cut into excessively minute fragments and 

 gathered into small heaps to serve as "mushroom gardens," in which 

 a fungus (Rozites gongylophom) is cultivated to furnish food for the 

 colony. Four species of ants (genus Atta) are found to grow the 

 same fungus. In all cases a small space is left between the "mush- 

 room garden " and the outer wall of the nest, and the beds are never 

 formed in an exposed position. The material collected by the ants 

 naturally contains spores of other fungi than their special kind, and 

 in cultivations prepared by Moller these appeared and developed. 

 In the nests, however, but the one kind is allowed to grow ; the ants 

 appear to weed out all but their special food. Over the upper 

 surface of the " garden " are numerous small white bodies, formed by 

 masses of swollen ends of fungus hyphae, which the ants appear to 

 produce by some special culture. These masses are what the ants 

 feed upon, they never appear to eat the fragments of leaves, which 

 form the fungus-beds. When they take a journey they carry with 



