The other reviewers commented on the main subject of this book - the question of inheritance. However, the Appendix has a fascinating account of Kammerer's work on serial coincidence, of "like and like" happening together. Kammerer spent long walks observing people and things, and determined that similar events happen together. For example, in one of his files he notes, two soldiers, both 19 years old, both born in Silesia, both volunteers in the transport corps, both admitted to the same hospital in 1915, both victims of pneumonia, and both named Franz Richter. He found lots of these coincidences, and claimed that this is the way the world is structured. In fact, these are not coincidences, but evidence of "The Law of the Series." Sounds weird, but he took this seriously. The Appendix in The Case of the Mid Wife Toad gives an account of this bizarre research project of Paul Kammerer.