Miscellaneous. 191 



fcst that the ants showed an accnrate sense of direction in markin"' 

 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 accurately 

 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 

 their paths were carried through the jungle of bracken and 

 various other wood-plants. The same fact appears to indicate that 

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

 sight *. It would perhaps 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. Enr/ineermg of Texas Cutting-Ants. — The author in this con- 

 nexion alluded to an observation which has heretofore been placed 

 on record f describing an underground route of the cutting- ant of 

 Texas (Aitafirveas). This route extended 448 feet, entirely beneath 

 the surface of the earth, at some places as deep as 6 feet, and having 

 an average depth of 18 inches. From the points at which the ants 

 came to the surface the road was continued in a straight line 185 

 feet further to a tree in a gentleman's private grounds, which the 

 ants were engaged in defoliating. The entire length of the roadway 

 was thus 669 feet, and the path as laid out by a young engineer 

 who assisted in the observation shows scarcely less deflection from a 

 straight course than that of the rufous ants recorded in the above 

 observation. 



4. Sentinels. — The longest of the three trails alluded to made by 

 the Scotch ants terminated upon an oak-tree, which was also occu- 

 pied by a column of ants from a neighbouring hill. The two columns 

 rigidly maintained their places on opposite sides of the trunk. Sen- 

 tinels were scattered along either margin of both columns, and these 

 exhibited great watchfulness and sensitiveness to the approach of 

 any object. The author, on approaching his finger to these sentinels, 

 observed that they seemed to perceive his finger when it reached a 

 point an inch or an inch an a half distant from the bark. At once 

 the ants thrust out their antennae, extended their heads, then the 

 two front legs, and finally the middle legs, thus hanging to the bark 

 of the tree by the hind legs alone, the abdomen being slightly turned 

 underneath the body, as though prepared to eject formic acid upon 

 any adversary. In one case at least the ant hung to the bark by 

 one hind foot alone, extending the whole body in a perpendicular 

 direction from the surface of the tree It presented a grotesque 

 appearance, and exhibited every sign of eagerness and vigilance in 

 the discharge of its duty as watchman. 



• The vision of ants is probably limited within a very short distance 

 from the eyes ; under any circumstances, therefore, it could have but 



little influence in determining such a phenomenon as here recorded 



H. C.McO. 



t See the author's ' Tenants of an Old Farm/ p. 264, fig. 90. 



