1932 ] Distribution of Formica ulkei 133 
luminometer shows an average of 2047 foot candles on the 
open margin and 1963 foot candles in the forest clearing as 
opposed to 31 foot candles on the shaded forest floor. 
3. The distribution of the mounds is directly correlated 
with light intensity and- attendant temperature conditions. 
Apparently a certan range of light intensity is a positively 
limiting factor in the location of these ant mounds. 
4. Soil moisture limits the distribution of the mounds in 
such a way that it is considered in the role of a negatively 
limiting factor. 
5. Several other interesting aspects of the complete eco- 
logical analysis of this unusual group of ant mounds are 
suggested for further study. 
Literature Cited 
Andrews, E. A. 1926. Sequential distribution of Formica 
exsectoides F. Psyche, xxxii, pp. 12:7-150. 
— _ — — ■ — 1927. Ant-mounds as to temperature and 
sunshine. Journal of Morphology and Physiology, xliv, 
pp, 1-21. 
— — 1928. Injuries to vegetation by mound- 
building ants. American Naturalist, lxii, pp. 63-75. 
Cowles, H. C. 1901. The plant societies of Chicago and 
vicinity. Bull. Geog. Soc. Chicago; also Botanical Ga- 
zette, xxxi. 
Dreyer, W. A. 1932. The effect of hibernation and seasonal 
variation of temperature on the respiratory exchange 
of Formica ulkei Emery. Physiological Zoology, v, No. 
2, pp. 301-331. 
Holmquist, A. M. 1928. Notes on the life-history and hab- 
its of the mound-building ant, Formica ulkei Emery. 
Ecology, ix, No. 1, pp. 70-87. 
Park, Orlando 1929. Ecological observations upon the 
myrmecocoles of Formica ulkei Emery, especially Lep- 
tinus testaceus Mueller. Psyche, xxxvi, No. 3, pp. 
195-215. 
Park, Thomas 1929. Notes on the relationship between 
Formica idkei Emery and Solenopsis molesta Say. En- 
tomological News, xl, No. 10, pp. 325-326. 
