1925 ] 
Growth of Ant Mounds 
87 
over the mound and even climb up and kill branches of this vi ne 
and of catbriar that may project over the mound though some 
feet above its surface. 
Summary. 
In a mound of Formica excestoides measured at intervals 
during nineteen years the growth was not constant but fluctuat- 
ing in rate. In the earlier years increase was very slow, in the 
later years very fast. Interruptions in growth and diminution 
in proportions may to some extent be referred to external inter- 
ferences, but probably in part to lack of steady success of the 
community. Other small incipient mounds start at the same 
slow rate. Mature mounds require many years for completion 
to full size. 
In the first two or three years the material of the mound is 
mined from the subsoil, but later more surface soil and collected 
fragments of vegetable matter are added to the pile. 
The rate of growth in reconstruction after injury to, or 
removal of part of, the mound is much greater than the usual 
rate of growth. Comparison with other mounds suggests the 
rate of growth to be strongly an individual character of each 
community under its own complex environment. 
