There are many collateral observations recorded both by de Vries and others which have a bearing on the problems, but they do not yet fall into a coherent scheme. For example, we cannot yet represent the formation of _laeta_ and _velutina_ from the various species fertilised by _Lamarckiana_ [M]. That this is not due to any special property associated with the pollen of _Lamarckiana_ is shown by the fact that a species called _Hookeri_ gives _laeta_ and _velutina_ in both its reciprocal crosses with _Lamarckiana_ (de Vries, 1909, p. 3), and also by the similar fact that _Lamarckiana_ [F] fertilised by the pollen of a peculiar race of _biennis_ named _biennis Chicago_ throws the same types. Before these very complicated phenomena can be usefully discussed particulars must be provided as to the individuality of the various plants used. This criticism applies to much of the work which de Vries has lately published, for, as we now know familiarly, plants to which the same name applies can be quite different in genetic composition. Attention should also be called to one curiously paradoxical series of results. When the dwarf "mutant" of _Lamarckiana_ which de Vries names "_nanella_" is used as father on _muricata_, F_{1} consists of _laeta_ and _velutina_ in approximately equal numbers. Both forms breed true to their special characteristics, but _velutina_ throws dwarfs of its own type, while _laeta_ does not throw dwarfs. Subsequent investigation of the properties of these types has led to some remarkable conclusions, and it was in a study of these plants that de Vries first came upon the phenomena of dissimilarity between the factors borne by the male and female cells of the same plant, a condition which had been recently detected in the Stocks as a result of Miss Saunders's investigations. The details are very remarkable. We have first the fact that _muricata_ [F] × dwarf _nanella_ [M] gives about 50 per cent. _laeta_ and about 50 per cent. of _velutina_. As regards _Velutina_ it was shown that: Talls, Dwarfs, per cent. per cent. 1. Velutina selfed gave 38 62 {Velutina [F] × dwarf nanella [M] gave 39 61 2.{ do. × do. gave 49 51 { do. × dwarf [M] derived from velutina gave 43 57 3. Dwarfs × velutina [M] gave -- all dwarfs