A data set from Oehlert (2000) \emph{A First Course in Design and
Analysis of Experiments}, New York: W. H. Freeman.

Data originally from Dale, T. B. (1992).  Biological and chemical
effects of acidified snowmelt on seasonal wetlands in Minnesota.
Master's thesis, University of Minnesota.

Number of Copepoda removed from 6 wetland soils after
simulated snowmelt. The first three values are at a reduced pH,
the last three at a neutral pH.