28 INSECTS 



use of both sight and smell ; but it is in the latter that they place most confidence, 

 for if the object be removed only the space of an inch from its position, the ant in 

 search of it will make a number of cross journeys over the old resting-place before 

 it is successful. The scent, too, seems to be rather that left by former footsteps 

 than proceeding from the object itself. This sense of smell, and perhaps touch 

 combined, is obviously manifested in the caressing or recognition of friends with 

 the delicate antennae. The mysterious sense of direction is, after all, but sensitive- 

 ness to the direction in which the rays of light fall from a luminous object, and, 

 as such, is but a form of sight. This is proved as follows : Ants made to cross 

 a wooden bridge would, in most cases, instantly turn round, if their heads were 

 turned in an opposite direction, by the bridge being made to rotate on a point. 

 And they would at once lose the sense of direction if light was shut out from the 

 artificial tract prepared for them, while if the candle were moved round in the 

 same direction as the bridge over which they travelled, though the direction be 

 changed, the ant does not become aware of it, because the rays of light fall from 

 the same point. Nevertheless, the sense of smell is evidently the stronger, for 

 ants carrying larvae from a cup to the nest still continue their course, although the 

 board on which they are travelling be turned right round. They follow the scent 

 of former tracks rather than take notice of the direction in which the light falls. 



O 



It is obvious that without some faculty representing, at anyrate, the rudi- 

 ments of memory, ants would not be able to recognise even the scent left by 

 comrades on the ground, nor would they persistently seek for an object which 

 had been removed. They exhibit, however, all the phenomena of true memory. 

 A fact, by repetition, becomes more firmly fixed as a sense-impression on their 

 brains. It fades away if not refreshed. Evidence in favour of a highly-developed 

 sense of memory is furnished by the fact that ants from a certain nest were in 

 the habit of journeying year by year, during the season of activity, to a chemist's 

 shop, six hundred yards distant, to a syrup-jar. It is scarcely likely that the jar 

 was found every year by fresh ants, so that memory alone will account for the 

 circumstance. It is perhaps in the recognition of friends, however, that ants 

 manifest the most extraordinary powers of memory. They invariably recognise a 

 friend, while a stranger is almost instantly slain. Ants held captive for months, 

 and returned to the nest, are recognised as lost friends, and caressed with the 

 antennae. This recognition might be merely a matter of the well-known odour of 

 a friend; but even then it must be a national smell, for it is scarcely possible 

 that each can recognise the personal scent of every individual. Not only do they 

 recognise the perfect ants, but even the offspring, or eggs, removed and hatched in 

 other nests, and returned home full grown, are recognised as kith and kin, while 

 their foster-mothers are slain. One can hardly suppose that the scent, unless 

 such be inherited, would account for such recognition. 



Whereas ants show evidence of such feelings as rage and combativeness, the 

 emotion of sympathy is by no means as constant or intense as might be supposed 

 from their general intelligence and power of recognising friends. Mutilated ants, 

 and those in difficulties, are passed by on the other side ; but an intoxicated ant 

 staggering in its tracks does not fail to excite astonishment, and is carried off as 

 a sort of curiosity to the nest. Chloroformed ants, however, are dropped into the 



