ANTS — KEEPING- APHIDES. 
ei 
principles, such a class of facts is to be met ; for it is cer- 
tainly difficult to understand the manner in which this 
instinct, so beneficial to the ants, can have arisen in the 
aphides, to which it does not appear, at first sight, to offer 
any advantages. Mr. Darwin meets the difficulty thus : 
6 Although there is no evidence that any animal performs 
m action for the exclusive good of another species, yet 
each tries to take advantage of the instincts of others 
and 6 as the secretion is extremely viscid, it is no doubt a 
convenience to the aphides to have it removed ; therefore 
probably they do not excrete solely for the good of the 
ants .’ 1 
Some ants which keep aphides build covered ways, or 
tunnels, to the trees or shrubs where the aphides live. 
Forel saw a tunnel of this kind which was taken up a wall 
and down again on the other side, in order to secure a 
safe covered way from the nest to the aphides. Occasion- 
ally such covered ways, or tubes, are continued so as to 
enclose the stems of the plants on which the aphides live. 
The latter are thus imprisoned by the walls of the tube, 
which, however, expand where they take on this additional 
function of stabling the aphides, so that these insects are 
really confined in tolerably large chambers. The doors of 
these chambers are too small to allow the aphides to escape, 
while large enough for the ants to pass in and out. Forel 
saw such a prison or stable shaped like a cocoon, and 
about a centimetre long, which was hanging on the branch 
of a tree, and contained aphides carefully tended by the 
ants. Huber records similar observations. 
Sir John Lubbock has made an interesting addition to 
our knowledge respecting this habit as practised by a 
certain species of ant ( Lasius flavus ), which departs in a 
very remarkable manner from the habit as practised by 
other species. He says : ‘ The ants took the greatest care 
of these eggs, carrying them off to the lower chambers 
with the utmost haste when the nest was disturbed . 5 But 
the most interesting of Sir John Lubbock’s observations 
in this connection is new, and reveals an astonishing 
Origin of Sjsedes, 6th ed. pp. 207-8. 
i 
