In connexion with these considerations I may mention that Vilmorin makes the interesting statement that most peas retain their vitality three years, dying as a rule rapidly after that time is passed, though occasionally seeds seven or eight years old are alive; but that _wrinkled_ peas germinate as a rule less well than round, and do not retain their vitality so long as the round. Vilmorin-Andrieux, _Plantes Potagères_, 1883, p. 423. Similar statements regarding the behaviour of wrinkled peas in India are made by Firminger, _Gardening for India_, 3rd ed. 1874, p. 146. In respect of _shape_ the seeds of a variety otherwise stable are as a rule fairly uniform, the co-existence of both shapes and of intermediates between them in the same variety is not infrequent. As Professor Weldon has said, _Telephone_ is a good example of an extreme case of mixture of both colours and shapes. _William I._ is another. It may be mentioned that regular dimorphism in respect of shape is not so common as dimorphism in respect of colour. Of great numbers of varieties seen at Messrs Suttons’ I saw none so distinctly dimorphic in shape as _William I._ which nevertheless contains all grades commonly. So far I have spoken of the shapes of ordinary English culinary peas. But if we extend our observations to the shapes of _large-seeded_ peas, which occur for the most part among the sugar-peas (_mange-touts_), of the “grey” peas with coloured flowers, etc., there are fresh complications to be considered. Professor Weldon does not wholly avoid these (as Mendel did in regard to shape) and we will follow him through his difficulties hereafter. For the present let me say that the classes _round_ and _wrinkled_ are not readily applicable to those other varieties and are not so applied either by Mendel or other practical writers on these subjects. To use the terms indicated in the Introduction, _seed-shape_ depends on more than one pair of allelomorphs--possibly on several. _Stability and Variability._