Hugo de Vries claimed that he had discovered Mendel's laws before he found Mendel's paper. De Vries's first ratios, published in 1897, for the second generation of hybrids were 2/3:1/3 and 80%:20%. By 1900, both of these ratios had become 3:1. These changing ratios suggest that as late as 1897 de Vries had not discovered the laws, although he asserted, from 1900 on, that he had found the laws in 1896. An Appendix details de Vries's Mendelian experiments as described in (...) the original edition of volume two of Die Mutationstheorie, but omitted entirely from the English translation. (shrink)

New concepts, or new and better formulations of old concepts, are essential for scientific progress. This paper is intended to focus attention on two phases of natural processes and human activities which have a variety of names, and by giving them neutral names, to deprive them of their emotional flavour. As a result I hope that two evolutionary principles of some generality will become apparent.

Three questions of major historical interest may be asked concerning the neglect and the rediscovery of Mendel's work.1. Why was it so little noticed between its publication in 1866 and its rediscovery in 1900?2. What factors determined its rediscovery?3. What factors favoured the rapid growth of Mendelian genetics?It is with the second and third of these questions that this paper is concerned.