1925] Weight of Vegetation Transported by Fungus Ants 227 
THE WEIGHT OF VEGETATION TRANSPORTED BY 
TROPICAL FUNGUS ANTS. 
By G. H. Parkar. 
Zoological Laboratory, Harvard University. 
No one can view a nest of active tropical fungus ants without 
being impressed by the unusual exhibition of transportation. 
Converging narrow paths are crowded with myriads of ants 
many of the incoming members of which carry above their 
heads the fragments of leaves, bits of stems and the like destined 
to serve as the soil on which the colony will raise its food. Such a 
spectacle came to my attention not far from the Barro Colorado 
Island Laboratory in Gatun Lake, at the Panama Canal. The 
colony was in an open part of the jungle about a quarter of a 
mile from the laboratory and easily accessible by a trail. At 
this laboratory, which is maintained by the Institute for Re- 
search in Tropical America, I had the opportunity of studying 
this and many other features of equatorial life. 
The nest was inhabited by the common funghs ant of the 
region, Atta columbica Guer., and comprised an approximately 
circular area of hummocky soil some twelve to fifteen feet in 
diameter. Into this area from various parts of the jungle led in 
all five ant-roads over which varying numbers of ants passed in 
and out with their burdens. It was comparatively easy to stand 
at a given point by one of these roads and, with a watch in the 
hand, count the number of ants with leaf fragments that passed 
toward the nest in a minute. Twenty feuch counts were made on 
each of the five roads. 
In the most densely frequented road the numbers of leaf 
fragments carried past the observer in a minute varied from 151 
to 184 and averaged 162.8. In the second most populous road 
the extremes were 52 and 81 and the average 69. In the third 
the numbers varied between 49 and 61 and averaged 53; in the 
fourth the extremes were 1 and 6, and the average 3 . 2, and in the 
fifth, which descended from a small tree that rose out of the nest, 
the numbers varied from 0 to 5, and averaged 2.2. As these five 
roads were separate pathways leading into the nest, the sum of 
