The Pocket Gopher. 139 



ground was fairly well soaked by recent rains. The method 

 of determining results in all cases was to open the burrow some 

 hours after the introduction of the gas and then visit the spot 

 a little later to note whether the opening had been closed. As 

 indicated above, in twenty-six out of thirty cases it was found 

 that fresh dirt had been pushed into the opening, showing that 

 the occupant of the burrow was uninjured. In a series of ex- 

 periments conducted recently at Alden, Kan., with the plains 

 pocket gopher, ten out of twelve openings were promptly closed 

 after the burrows had been thoroughly fumigated. 



In one experiment, undertaken with particular care, a line of 

 mounds on a gentle slope o'f prairie sod was selected as indi- 

 cating a single, simple burrow. At a point 100 feet down the 

 slope from the last mound in the line an opening was made 

 into the runway and the latter sufficiently enlarged to receive 

 a cat. In four minutes from the time the operator began 

 pumping gas at a second opening 100 feet distant the cat 

 yielded its nine lives separately and individually to the cause of 

 science. Not so the gopher, however. After pumping gas into 

 two openings made below the point where the cat had been 

 placed, the field was abandoned until the next day, when it 

 was found that the gopher, or gophers, had packed some of the 

 openings and were defiantly throwing up fresh mounds. 



No experiments in forcing fumes of burning sulfur into the 

 burrows were undertaken, but in a number of the trials men- 

 tioned above the charge of carbon-bisulfid vapor was exploded 

 by dropping a lighted match into the opening of the burrow 

 after removing the can to a safe distance. The gas resulting 

 from the combustion of the carbon-bisulfid vapor is the same 

 as that produced by burning sulfur sulfur dioxid. Although 

 no disaster to the gopher seemed to follow these explosions, 

 the distance to which the gas had penetrated and the length 

 and intricacies of the burrows was demonstrated by the pres- 

 ence of smoke or loose earth forced out at weak places. 



In the case of the experiment with the cat, cited above, the 

 investigator who furnished the apparatus for the trial under- 

 took to increase the efficiency of the gas by adding flowers of 

 sulfur to the liquid in the can. This served only to clog the 

 machine, however, as none of the sulfur can be dissolved in 

 the carbon-bisulfid. A certain manufacturer of a proprietary 

 liquid for destroying pocket gophers by fumigation claims 



