ANTS NESTS. 



377 



notice what inexpressible difficulty it has in making its way with a 

 load through the thicket of blades of grass in a meadow, how 

 constantly the load is getting wedged between them, and what 

 incredible patience and perseverance the insect displays in the 

 effort to go forward to understand the object of the roads. The 

 road-building of Formica prate?isis presents one of the most won- 

 derful displays of animal instinct that I know of Several such 

 roads radiate with great regularity from one of the larger nests of 

 this species lying in a meadow ; I have counted from three to 

 eight and even twelve of them (so large a number is rare and 

 occurs only in the case of very large nests). It can be seen that 

 these roads lead mostly to trees or shrubs on which the ants climb 

 up in multitudes in order to milk the plant lice. The road itself 

 is kept very clean, is from 2 to 4 centimetres in width, and is made 

 more or less concave laterally. Not only is no movable object 

 allowed upon it, not only is it kept always clean and in good order, 

 but the ants, with the expenditure of incredible toil and strength, 

 saw off with their mandibles every blade of grass that attempts to 

 grow in the road, as they previously sawed off all those which 

 were in existence when it was first constructed. Where the 

 tufts of grass are too thick and strong, they go around them, it is 

 true ; but the roads usually run comparatively straight to their 

 destination. Many of them are gradually lost in the grass ; but 

 as a rule they can be followed to a distance of twenty, thirty, 

 forty, and in many cases fifty metres from the nest. One must 

 watch long, closely, and above all in the spring, to see and under- 

 stand the road building, and to avoid the impression that the 

 road, as certain authors have thought, comes into existence of 

 itself through the footsteps of the ants. These roads are very 

 numerously frequented. All the building materials and forage 

 are first despatched to the nearest road, so that they may be 

 carried comfortably from there to the nest. As Formica pratensis 

 has very defective powers of smell, and is not skilful in finding 

 its way, the roads are also of great advantage to it in this respect. 

 There are only two directions on them, and it is no longer com- 

 pelled to search laboriously for the right way. It can be seen, 

 too, how rapidly and confidently the ants move to and fro on 

 their roads, in contrast to their behaviour in the grass. (Com- 



