1903.] NATURAL SCIENCES OF PHILADELPHIA. 619 



were from one to three minutes in struggling across. Sometimes the 

 burdened swimmer became completely submerged, and when this 

 happened she abandoned the burden, which floated, while the ant 

 scrambled ashore. It was evident that the strength of the burdened 

 ants was exhausted in reaching the edge way, though they crossed in 

 a straight line at right angles to the length of the channel. They had 

 chosen, as the main crossing-place, the narrowest part of the channel, 

 which was on the side of the board opposite the source of light, a 

 northern window. 



The next morning I thoroughly cleansed all parts of the board; 

 turned the narrowest part of the channel to the opposite side, the 

 northern ; replaced it on the table ; filled the channel with clean water ; 

 enclosed the board and an area half its size by a wall of plaster of Paris.^ 

 and set within the area one of my artificial nests, having an entrance 

 four millimeters wide at a distance of fifteen centimeters from the 

 boal'd. On the island I then put some ant-food, three hundred workers, 

 twelve queens, of whom five had long been deprived of antennae, and 

 a large teaspoonful of eggs, larv£e and pupse. These ants were from 

 the same colony as those that had gone to the crevice. The only ants 

 in the arena were those on the island. My preparations were completed 

 at eleven o'clock, and the first ant, a small adult worker, crossed 

 the channel at a quarter before twelve o'clock. The second ant 

 crossed, in another place, fifteen minutes later, and a third crossed 

 after another half -hour. At three o'clock four more workers and 

 three queens had crossed. The workers appeared to be seeking 

 a habitation, and the queens were roaming on the edgeway. The 

 first ant to enter the nest was a worker that chanced to find the 

 small entrance at five o'clock, when many ants were prospecting in 

 the area. Before the discovery of the dark, warm, humid interior 

 of the new nest, and up to seven o'clock, no ant had returned across 

 the channel. 



The ensuing morning, at six o'clock, the ants were transporting 

 3^oung across the channel, mainly at its narrowest part, on the north 

 side and toward the light. The eggs, larvae and pupte were piled on 

 the south side of the island farthest from the light, and many ants were 

 covering the pile with their bodies. Rescuers ran along the edgeway, 

 or held to it with their hinder feet and stretched themselves over the 

 water, as if with the purpose of securing flotsam. If they rendered 

 aid to struggling swimmers other than the queens, it was merely by 



■' For el's method of preventing the escape of ants. 



