Contributions to Zoology, 86 (4) – 2017Jacques J. M. van Alphen; Jan W. Arntzen: The case of the midwife toad revisited

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Appendix 2

Kammerer (1911: 101-104, reproduced in Appendix I) reports on four experiments with clearly stipulated numerical results for male as well as for female midwife toads. The results for the sexes are however not independent as illustrated by equal sample sizes. Moreover, if a female would decide to mate in water the male can only follow, etc. The results for the males are sometimes difficult to categorize, such as for example the acceptance of a batch of embryos followed by a rejection. Similarly, ‘not accepting’ a batch is difficult to distinguish from ‘no action at all’. Conversely, the categorization of the female data is straightforward because egg-size and egg-number distributions are strongly bimodal and have corresponding class allocations. Also Kammerer’s presentation is unambiguous, e.g. with numbers within classes separated by commas and classes separated by a semicolon. We therefore choose to only analyze the data for the female midwife toads.

Kammerer (1913: 131, reproduced in Appendix I) provides numerical results on the crossing between the ‘typical form’ of the fire salamander and the form ‘taeniata’. For ‘pair d’ the numbers for the typical form add up to 71, instead of the reported value of 80. The only single-character typographical error that would explain the discrepancy is that ‘20 typ.’ should read ’29 typ.’. In Figure 2 the printed data are reported and the correction is presented as an alternative (with no repercussions on the statistical interpretation).