1887.] NATURAL SCIENCES OF PHILADELPHIA. 337 



column made a detour of about six inches from the straiglit line, but 

 an al)audoned path, continuous with t]ie main road, which had 

 apparently been used at a recent date, was traced for a considerable 

 distance further without any deflection. No. 3 was the longest road 

 of the three, being 34 paces in length. It extended for six paces in 

 a straight line from the nest, at which point it touched an old stump 

 which evidently deflected the path at a slight angle. From this 

 point it was again continued in a nearly straight line as far as the 

 beaten foot-path tlirough the wood. Here the ant trail was oblitera- 

 ted by the friction of passing human feet, but the ants themselves 

 thronged over the pathway in a column much broadened by continual 

 interference and loss caused by foot passengers. The trail w\as, how- 

 ever, resumed at a point nearly opposite that at which it touched 

 the path, and was continued again in a straight line six paces 

 further to the tree, where it terminated. When the entire 

 trail Avas staked off" it was found that its terminus deviated less than 

 three feet from a straight line drawn from the point of departure at 

 the ant hill. The greater deviation in this case seemed evidently to 

 have been caused by the peculiar difiiculties in the chosen track. 

 The three roads so radiated from the nest that they were included 

 within about one quadrant of a circle, of which the two shorter 

 trails might represent the radial boundaries of the quadrant, while 

 the longer trail was drawn nearly midway between the two. 



Taking the results of the three observations together it is mani- 

 fest that the ants showed an accurate sense of direction in marking 

 out and following their approaches to the trees. It would be scarcely 

 reasonable to attribute such mathematical accuracy as above shown 

 to mere accident. The roads in point of directness were as accurate- 

 ly laid down as ordinary roads made by the engineering skill of 

 men. The skill of the ants was all the more apparent from the fact 

 that iheir paths w^ere carried through the jungle of bracken and 

 various other wood plants. The same flxct appears to indicate that 

 the insects could not have been largely directed by the sense of 

 sight.* It would perliaps be idle to speculate upon the manner in 

 which this feat of emmet engineering was accomplished, as there 

 were no facts observed which give a clue to the mode of proceeding, 

 but the problem is one well worth study by naturalists on the 

 ground. 



3. Engineering of Texas Catting Ants. Dr. McCook in this con- 

 nection alluded to an observation which has heretofore been placed 

 on record ' describins; an undero-round route of the cutting ant of 

 Texas, Attn fervens. This route extended 448 feet, entirely beneath 

 the surface of the earth, at some places as deep as six feet, and hav- 



* The vision of ants is probably limited witiiin a very short (iistance from 

 the eyes; under any circumstances, therefore, it could have but little influence in 

 determining such a phenomenon as here recorded. H. C. McC. 



^ See the anther's Tenants of an Old Farm, p. 2()4; fig. 90. 



