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accompanied by variations in mound form and size. Howse (1979) 
gives several different examples of termite species which build very 
different mounds in different regions. Macrotennes subhvalinus in 
western Uganda builds mounds with very thick walls and no open- 
ings but on the Serengeti Plains, where the soil is volcanic ash, the 
mounds are low with many pit-like openings. In the semi-arid 
regions of eastern Africa they are different again, being steeple- 
shaped and constructed around a central chimney. Even though 
regional differences can exist, the characteristics of mounds investi- 
gated in this study showed a remarkable consistency throughout the 
cerrado region reinforcing observations by Emerson (1938). 
In constructing a mound, galleries are excavated within the soil 
by the termites and particles are often transported from considera- 
ble depth and incorporated in the epigeal portion of the mound. 
This not only increases aeration of the soil but can also alter its 
chemical composition (Lee and Wood 1971). Soil used in building is 
reinforced with excreta and in some instances wood and other plant 
material. 
Studies on the chemical composition of termite mounds in the 
cerrado have recently been started in Brasilia. Preliminary results 
indicate that both Ve/ocitermes and Armitermes mounds have much 
higher concentrations of calcium, phosphorus, potassium and alu- 
minum than the soil surrounding the mound (Curado et al. in 
prep.). However, an analysis of Table 5 shows that the materials 
used in mound building are not directly related to the hardness of 
the outer layer of the mound. Such factors as the way in which the 
material is deposited by the workers at the actual site of construc- 
tion as well as the size and arrangement of galleries and the thick- 
ness of walls also contribute to the overall hardness of the mound. 
The mounds are constructed entirely by the worker caste. This 
caste takes little active role in the defense of the mound, a role 
performed by the soldier caste. The proportion of these two castes 
varies with the species and is apparently finely regulated by phero- 
mones produced by the queen and the soldiers (Luscher 1961). 
Haverty (1977), in a comprehensive work, summarized the data 
available on the relative proportion of workers and soldiers in 1 12 
species of termites. Unfortunately, many of these data, gathered by 
different investigators, are not strictly comparable because of differ- 
ences in sampling techniques and types of groups sampled. The 
