REPORT OF THE SOCIETY 55 



ant were endowed with reason, I should say that it performs a good act against its 

 will. What it seeks first and even exclusively is its own good, and all its inter- 

 course with the aphids bears the marks of the purest egoism. 



It remains for us to see some of the evils which the plant suffers. I shall col- 

 lect them under three heads : the protection of the aphids ; the propagation of the 

 aphids; the isolation of the plant. 



1. Protection of the aphids. This protection is twofold; from the inclem- 

 encies of the weather, and from their natural enemies. The protection against 

 the weather in summer has but little importance; it is otherwise in the spring and 

 autumn. It frequently happens that aphids hatched early in the spring are ex- 

 posed to death from a late frost, if left on the plant or on the surface of the ground. 

 The ants, however, often drag them into their nests. Here they are sheltered 

 from the cold, and may attack the roots of the plants. In the autumn, the last 

 of the last generation would be frozen before reproduction could take place, were 

 they not interfered with; but thanks to the enforced confinement their complete 

 development is rendered possible. This captivity has another advantage which 

 extends even to the individuals that would have the time to lay their eggs before 

 the frost, namely, the eggs are less exposed and are guarded by the ants when 

 necessary. This brings me to the discussion of the protection from their natural 

 enemies. 



Many naturalists have asserted that insects which live on aphids are driven 

 away by the ants. I willingly admit this, but with some restrictions. In the first 

 place, are we certain that this is done in order to protect the aphids? It may well 

 be that the ant is merely taking precautionary measures to avoid an attack which 

 it believes is directed against itself. This hypothesis, I think, may enable us to 

 interpret many of the facts, and moreover it affords an explanation of the mania 

 for imprisoning aphids in the middle of summer. Further we must not confuse a 

 double flight jwith the pursuit of a fugitive. An ant at the top of a plant suddenly 

 perceiving an insect climbing up, and attributing evil intentions to it, will hasten 

 to descend; the insect fearing for itself will retreat, and we have thus two fugitives 

 hurrying in the same direction. / 



Everything happens as if the ant were in pursuit of a fugitive insect. I was 

 able to witness this spectacle by forcing a harmless insect up the plant. If the in- 

 sect be carnivorous and of respectable size the ant does not wait for it to manifest its 

 intentions. The following is a convincing proof that we must not exaggerate 

 the courage of the ant. I took some ants living among the aphids of the apple 

 tree and placed them on plants infested by the Rudbeckia aphis. They moved 

 about slowly at first, but as soon as they met the aphids there was an indescribable 

 panic; in most instances indeed they threw themselves to the ground to escape 

 more quickly. Yet what could cause them less injury then an aphis? We must not 



