Yet by some power of observation, perhaps superior in this respect to the abilities of greater creatures, the tiny thing guides its footsteps without faltering down yonder to the nest in the hollow on the bank of the ploughed field. I say by observation, and the exercise of faculties resembling those of the mind, because I have many times tried the supposed unerring instinct of the ant, and found it fail: therefore it must possess a power of correcting error which is the prerogative of reason. Ants cannot, under certain conditions, distinguish their own special haunts. Across a garden path I frequented there was the track of innumerable ants; their ceaseless journeyings had worn a visible path leading from the border on one side to the border on the other, where was a tiny hole, into which they each disappeared in turn. Happily, the garden was neglected, otherwise the besom of the gardener would have swept away all traces of the highway they had made. Watching the stream of life pouring swiftly along the track, it seemed to me that, like men walking hurriedly in well-known streets, they took no note of marks or bearings, but followed each other unhesitatingly in the groove. When street-pavements are torn up, the human stream disperses and flows out on either side till it discovers by experience the most convenient makeshift passage. What would be the result if this Watling-street of the ants were interrupted? With a fragment of wood I rubbed out three inches of the path worn in the shallow film of soil deposited over the old gravel, smoothing that much down level. Instantly the crowd came to a stop. The foremost ant halted at the edge where the groove now terminated, turned round, and had an excited conversation with the next by means of their antennae; a third came up, a fourth and fifth--a crowd collected, in fact. Now, there was no real obstruction--nothing to prevent them from rushing across to the spot where the path recommenced. Why, then, did they pause? Why, presently, begin to explore, right and left, darting to one side and then to the other examining? Was it not because an old and acquired habit was suddenly uprooted? Surely infallible instinct could have carried them across the space of three inches without any trouble of investigation?