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1875.] Modern Entomology. | 229 
a cloud of thin smoke.”’ According to Burchell, this liquid, 
in some of the larger tropical species, burns and stains the 
hands to such an extent, that the capture of the insect 
requires considerable resolution. ‘The common Cychrus 
vostvatus projects, without any report, a drop of colourless 
liquid, which burns the skin, and which we suspec¢t to be 
formic acid in a very concentrated state. On this subject 
there is room for much interesting micro-chemical research. 
The existence of blind species of insects is a faét which 
leads to certain difficult questions. The author describes a 
blind beetle, Leptodérus sericeus, found, as far as is known, 
only in the caverns of Carinthia, which are inhabited; also 
of a blind spider (Obisium). Several ants also are blind, 
including several of the terrible Ecitons, in which family we 
recognise a curious instance of serial degradation as regards 
the organs of sight. LEczton legionis and predator are not 
blind, but, as Mr. Bates informs us, have eyes consisting 
each of a single lens, instead of the compound structure 
usual in inseéts. E. crassicornis has eyes sunk in rather 
deep sockets, and always avoids the light, moving in con- 
cealment under leaves. If obliged to cross a clear space, 
it constructs a covered way or tunnel with grains of earth, 
as do the equally blind soldiers and workers among the 
Termites. Eciton vastator has no eyes, although “the col- 
lapsed sockets are plainly visible,” whilst in Eciton ervatica 
both sockets and eyes have disappeared, leaving only a faint 
ring to mark the place where eyes are normally situated. 
It is curious that these totally blind species construct a 
covered way on coming into the open, proving that in some 
unknown manner they are aware of the presence of light. 
The question then arises, are these species blind, ab initio, 
being adapted to dark, subterranean abodes, or have they 
become blind by a process of gradual transformation? To 
us the facts of the case seem neither favourable to original 
‘adaptation”’ nor to “natural selection,” since, though 
eyes may in such situations be rarely or never of use, it is 
hard to see how their possession should be any inconve- 
nience. Other species, which lead underground lives, are 
well known to be furnished with eyes. It is quite conceiv- 
able, that in the course of many successive generations, the 
eyes should be atrophied by disuse. 
Where different geological formations meet, there the 
most interesting minerals are often found. Where land and 
water come in contact, there organic life is generally the 
richest and most varied. In an analogous manner, the 
boundary between two sciences often proves a fertile field 
