Did Paul Kammerer discover epigenetic inheritance? A modern look at the controversial midwife toad experiments.

The controversy surrounding the alleged Lamarckian fraud of Paul Kammerer's midwife toad experiments has intrigued generations of biologists. A re-examination of his descriptions of hybrid crosses of treated and nontreated toads reveals parent-of-origin effects like those documented in epigenetic inheritance. Modification of the extracellular matrix of the egg as described by Kammerer provides a plausible cause for altered gene methylation patterns. Traits such as altered egg and adult body size in Kammerer's "treated" toads are inherited epigenetically in other tetrapods. A preliminary model involving the environmental silencing of a maternally inherited allele can be attempted to explain the midwife toad experiments. Given available molecular tools and our current understanding of epigenetics, new experimentation with the midwife toad is strongly encouraged.