36 
Psyche 
[March 
breezes. The result is, therefore, quite unlike that predicted by the 
writer in 1963, for the movement of the leaves does not displace the 
foragers on them. Since I expected that there would be numerous 
displacements, the ground below the tree was cleared of weeds and 
smoothed so that any fallen forager would be easily visible. But, 
although observations were made several times a day over a period 
of six months, not a single forager was ever seen on the soil at the 
base of the tree. This statement needs further consideration for the 
foragers not only managed to avoid being displaced from the tree 
but they also refused to leave when foraging brought them near the 
soil. The trunk of the tree in which the nests were placed consisted 
of a single, large basal trunk about eighteen inches high, which 
divided into two secondary trunks to form a Y. The crown of the 
tree was thus divided into two portions and the most certain way to 
get from one to the other was to travel down one arm of the Y and 
up the other. This the foragers from the free nests regularly did. 
But in passing from one arm of the Y to the other the ants were 
often within a foot of the soil. As they are clearly aware of the 
presence of an observer at that distance it is inconceivable that they 
should not have been aware of the soil below them. Yet no forager 
was ever seen to descend to it. Since texanus is not known to nest 
in grapefruit trees, there is a possibility that this behavior was 
abnormal. If so it seems odd that the abnormality should have pre- 
vented the ants from doing the one thing that might have led them 
to a more acceptable nest site. In my opinion their behavior was 
normal and, if this is correct, we now have support for the view that 
texanus forages only in trees and that its presence on the ground 
may be regarded as the result of an accident. Moreover, there is 
reason to believe that such accidents are much less frequent than was 
formerly supposed. 
When a free colony of texanus is foraging actively it is impossible 
to keep track of the foragers, since they are scattered all over the 
crown of the tree. But if the beginning of foraging is observed in the 
morning it is possible to get some idea of the number of workers 
engaged in it by counting how many workers leave the nest before 
any return to it. On this basis the number of foragers was sur- 
prisingly small, for it appeared that there were seldom more than 
twenty outside the nest at the same time. More often there seemed 
to be no more than a dozen workers engagd in foraging. After a 
number of counts of this sort the writer came to the conclusion that 
even the most active of the free colonies must be a small one. It was, 
therefore, a surprise when this colony was exposed on April 1 1 , to 
