  We establish an exact relation between self-avoiding branched polymers in D+2
continuum dimensions and the hard-core continuum gas at negative activity in D
dimensions. We review conjectures and results on critical exponents for D+2 =
2,3,4 and show that they are corollaries of our result. We explain the
connection (first proposed by Parisi and Sourlas) between branched polymers in
D+2 dimensions and the Yang-Lee edge singularity in D dimensions.
