This is only one case among many similar ones seen in the Chinese Primrose. In others there is no doubt that more complex factors are at work, the subdivision of compound characters, and so on. The history of the “Giant Lavender” goes back many years and is not known with sufficient precision for our purposes, but like all these forms it originated from crossings among the old simple colour varieties of _sinensis_. VI. THE ARGUMENT BUILT ON EXCEPTIONS. So much for the enormous advance that the Mendelian principles already permit us to make. But what does Professor Weldon offer to substitute for all this? Nothing. Professor Weldon suggests that a study of ancestry will help us. Having recited Tschermak’s exceptions and the great irregularities seen in the _Telephone_ group, he writes: “Taking these results together with Laxton’s statements, and with the evidence afforded by the _Telephone_ group of hybrids, I think we can only conclude that segregation of seed-characters is not of universal occurrence among cross-bred peas, and that when it does occur, it may or may not follow Mendel’s law.” Premising that when pure types are used the exceptions form but a small part of the whole, and that any supposed absence of “segregation” may have been _variation_, this statement is perfectly sound. He proceeds:-- “The law of segregation, like the law of dominance, appears therefore to hold only for races of _particular ancestry_ [my italics]. In special cases, other formulae expressing segregation have been offered, especially by De Vries and by Tschermak for other plants, but these seem as little likely to prove generally valid as Mendel’s formula itself. “The fundamental mistake which vitiates all work based upon Mendel’s method is the neglect of ancestry, and the attempt to regard the whole effect upon offspring, produced by a particular parent, as due to the existence in the parent of particular structural characters; while the contradictory results obtained by those who have observed the offspring of parents identical in certain characters show clearly enough that not only the parents themselves, but their race, that is their ancestry, must be taken into account before the result of pairing them can be predicted.” In this passage the Mendelian view is none too precisely represented. I should rather have said that it was from Mendel, first of all men, that we have learnt _not_ to regard the effects produced on offspring “as due to the existence in the parent of particular structural characters.” We have come rather to disregard the particular structure of the parent except in so far as it may give us a guide as to the nature of its gametes.