(_a_) _Rimpau’s cases._ Professor Weldon quotes Rimpau as having crossed wrinkled and round peas[93] and found the second hybrid generation dimorphic as usual. The wrinkled peas were selected and sown and gave wrinkled peas _and round_ peas, becoming “true” to the wrinkled character in one case only in the fifth year, while in the second case--that of a _Telephone_ cross--there was a mixture of round and wrinkled similarly resulting from _wrinkled_ seed for two years, but the experiment was not continued. [93] In the first case _Knight’s Marrow_ with _Victoria_, both ways; in the second _Victoria_ with _Telephone_, both ways. These at first sight look like genuine exceptions. In reality, however, they are capable of a simple explanation. It must be remembered that Rimpau was working in ignorance of Mendel’s results, was not testing any rule, and was not on the look out for irregularities. Now all who have crossed wrinkled and round peas on even a moderate scale will have met with the fact that there is frequently _some_ wrinkling in the cross-bred seeds. Though round when compared with the true wrinkled, these are often somewhat more wrinkled than the round type, and in irregular degrees. For my own part I fully anticipate that we may find rare cases of complete blending in this respect though I do not as yet know one. Rimpau gives a photograph of eight peas (Fig. 146) which he says represent the wrinkled form derived from this cross. It is evident that these are not from _one pod_ but a miscellaneous selection. On close inspection it will be seen that while the remainder are shown with their _cotyledon_-surfaces upwards, the two peas at the lower end of the row are represented with their _hilar_-surfaces upwards. Remembering this it will be recognized that these two lower peas are in fact _not_ fully wrinkled peas but almost certainly _round_ “hybrids,” and the depression is merely that which is often seen in round peas (such as _Fillbasket_), squared by mutual pressure. Such peas, when sown, might of course give some round. As Tschermak writes ((37), p. 658), experience has shown him that cross-bred seeds with character transitional between “round” and “wrinkled” behave as hybrids, and have both wrinkled and round offspring, and he now reckons them accordingly with the round dominants. Note further the fact that Rimpau found the wrinkled form came true in the _fifth_ year, while the round gave at first more, later fewer, wrinkleds, not coming true till the _ninth_ year. This makes it quite clear that there _was_ dominance of the round form, but that the heterozygotes were not so sharply distinguishable from the two pure forms as to be separated at once by a person not on the look-out for the distinctions. Nevertheless there _was_ sufficient difference to lead to a practical distinction of the cross-breds both from the pure dominants and from the pure recessives.