438 TOWER, DARWINISM. 
of the two generations occurring in the following year. In all respects 
this is the most significant of all of the eliminating activities encoun- 
tered by these beetles. 
The general picture of one of these isolated colonies during the 
rainy season, as far as the numerical strength is concerned, shows 
the smallest adult population to be that which survives from aesti- 
vation, with a constantly increasing number of individuals in the 
colony up to the close of the rainy season, when they all disappear 
within a very few days with the onset of the dry season. The 
controlling eliminating process that holds these forms substantially 
at equilibrium, as far as abundance is concerned, through a period 
of years, depends upon what takes place during aestivation, so that 
the question in these animals is the same as it was in the plant, 
or, whether survival depends on chance position or upon favorable 
adaptive qualifications. 
The method used in making the tests was to collect all of the 
adults of a colony at the close of the rainy season, separate the 
males from the females in different containers, and then, with the 
container under a dark cloth, the individuals were drawn out at 
random, until both sexes were separated into two numerically equi- 
valent groups. Half the males and half the females were then put 
together and returned to the original colony, where they entered 
into aestivation as though they had never disturbed. A plot was 
selected in close proximity to the colony, differing from it as 
slightly as possible or not at all, spaded up fine to the depth of 
about two feet, the top leveled off smooth and covered with brush, 
bunches of grass and other native vegetation, into which were 
transplanted some of the food plants, and the whole inclosed either 


in a cloth or in an inexpensive wire cage. A native was hired to 
guard these plots, otherwise the cloth or the wire used was very 
prone to be rapidly appropriated for industrial uses. I remember 
one case with considerable amusement, in which such a plot was 
covered with a strong native cotton cloth, the only material available. 
To make it less conspicuous, it was generously spotted with fairly 
large splashes of black, green and gray paint. When I returned to 
Los Narancos the following spring, my cage was enclosing other 

