If we compare the individual characters of the hybrids with the corresponding characters of the two parent types, we find that they sometimes present intermediate structures, but are sometimes so near to one of the parent characters that the [corresponding] character of the other has receded considerably or almost evades observation. So, for instance, we see in one of the two forms of _H. Auricula_ ♀ x _H. aurantiacum_ ♂ pure yellow disc-florets; only the petals of the marginal florets are on the outside tinged with red to a scarcely noticeable degree: in the other on the contrary the colour of these florets comes very near to _H. aurantiacum_, only in the centre of the disc the orange red passes into a deep golden-yellow. This difference is noteworthy, for the flower-colour in _Hieracium_ has the value of a constant character. Other similar cases are to be found in the leaves, the peduncles, &c. If the hybrids are compared with the parent types as regards the sum total of their characters, then the two forms of _H. præaltum_ ♀ x _H. aurantiacum_ ♂ constitute approximately intermediate forms which do not agree in certain characters. On the contrary in _H. Auricula_ ♀ x _H. aurantiacum_ ♂ and in _H. Auricula_ ♀ x _H. pratense_ ♂ we see the forms widely divergent, so that one of them is nearer to the one and the other to the other parental type, while in the case of the last-named hybrid there is still a third which is almost precisely intermediate between them. The conviction is then forced on us that we have here only single terms in an unknown series which may be formed by the direct action of the pollen of one species on the egg-cells of another. 2. With a single exception the hybrids in question form seeds capable of germination. _H. echioides_ ♀ x _H. aurantiacum_ ♂ may be described as fully fertile; _H. præaltum_ ♀ x _H. flagellare_ ♂ as fertile; _H. præaltum_ ♀ x _H. aurantiacum_ ♂ and _H. Auricula_ ♀ x _H. pratense_ ♂ as partially fertile; _H. Auricula_ ♀ x _H. Pilosella_ ♂ as slightly fertile, and _H. Auricula_ ♀ x _H. aurantiacum_ ♂ as unfertile. Of the two forms of the last named hybrid, the red-flowered one was completely sterile, but from the yellow-flowered one a single well-formed seed was obtained. Moreover it must not pass unmentioned that among the seedlings of the partially fertile hybrid _H. præaltum_ ♀ x _H. aurantiacum_ ♂ there was one plant which possessed full fertility. [3.] As yet the offspring produced by self-fertilisation of the hybrids have not varied, but agree in their characters both with each other and with the hybrid plant from which they were derived. From _H. præaltum_ ♀ x _H. flagellare_ ♂ two generations have flowered; from _H. echioides_ ♀ x _H. aurantiacum_ ♂, _H. præaltum_ ♀ x _H. aurantiacum_ ♂, _H. Auricula_ ♀ x _H. Pilosella_ ♂ one generation in each case has flowered.