438 Mound-Making Ants of the Alleghenies. [July, 
gates. The doors are simply the surface openings of the galleries 
with which they correspond in size. 
_ Huber declares it to be one of the fixed habits of the fallow ant 
(F. rufa), of Switzerland, to close the gallery-doors ‘at night and 
re-open them in the morning. The most careful attention could 
discover no such behavior among the ants at Camp Riddle. At 
no time during the whole week was there observed any sign of 
attempt to close up the galleries. Even during the heavy storm 
of rain referred to, the doors which were closely examined at 
various hours of the night, remained open. It would have been 
more satisfactory could an observation have been made during a 
fall of rain in the day time, but I have little doubt on this point, 
. and none at-all on the ordinary night-condition of the doors. 
This is certainly a remarkable variation in habit. It may possibly 
be accounted for by the presence in Switzerland of some nocturnal 
enemy, from which the American congeners are free. 
Before taking up in detail the life habits of our mound builders, 
a comparison and contrast may be allowed which may give a 
popular illustration of the immense labors of the fallow ant. I 
have calculated the cubic contents of one of the largest hills to 
be, in round numbers, two millions of cubic inches. Let us 
estimate the bulk of an ant equal to that of a cylinder three- 
eighths of an inch high and one-sixteenth of an inch in diameter at 
the base. We have thirty-five one hundred thousandths of a cubic 
inch as the bulk of a single ant, or two thousand eight hundred and 
sixty insects to the solid inch. The size of the builder is there- 
fore to the size of the edifice as one to fifty-eight thousand millions, 
Let us compare this with a corresponding estimate of the work 
of man (taking his bulk at four cubic feet), as wrought upon the 
great pyramid, reckoned to contain two hundred and seventy-six 
millions of cubic feet. 
Man’s bulk to his building is as 1: 69 millions. 
The Ant’s Et a u fedo T 
The figures are given roundly, without strict verification ; they 
show vastly in favor of the mechanical energy and industry of the . 
insect, if such comparisons may be allowed to show any thing, 
which is perhaps doubtful. They may serve however to impress 
some minds more vividly than other methods, with the immense 
= activity which marks the wonderful realm of insect life. The 
-~ advantage is yet more striking when the period of time consumed 
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