THE POTATO AND NIGHTSHADE FAMILY. 54! 



the hybrids of D. ferox, allied to another species of the white 

 group, have brown stems and violet blossoms, it is because D. 

 forox itself possesses the germ of this colouring. In the pure 

 species the colouring remains in a rudimentary state, occupy- 

 ing only the small interval which extends from the commence- 

 ment of the root to the cotyledons ; in the hybrid it acquires 

 an enormous increase, extending over all parts of the plant, 

 and manifesting more especially its action on the flower.* 

 Here, then, is a first mode of variation, induced by the cross- 

 ing of two species, and which produces its effects on the first 

 hybrid generation. The second generation is about to offer 

 us variations of another kind, and still more remarkable. All 

 these hybrids, though sterile at the first seven or eight dicho- 

 tomies, were very fertile in those which developed later. Their 

 seeds, sown in the spring of 1875, gave me in the second gen- 

 eration 19 plants of D. feroci-lcevis, and 26 of D. lavi-ferox. 

 The two sets still resembled each other, but by a character 

 diametrically opposite to that which was the prominent trait of 

 the preceding generation. The most astonishing diversity of 

 feature succeeded the former great uniformity a diversity of 

 such an extent that, out of the 45 plants of which the two sets 

 were composed, no two were found which precisely resembled 

 each other. They differed in stature (in the proportion of one 

 to four), in habit, in the form of the leaves, the colouring of 

 the stem and flowers, the degree of fertility, the size of the 

 fruit, and the degree of aculeation. With the exception of a 

 single individual of the D. Icevi-ferox set, which had completely 

 reverted to D. Icevis with this slight difference, that there was 

 still at the base of the stem a circle of purplish violet not 

 one of these hybrids had sensibly approached this species, and 

 there was only a very small number in which one could recog- 

 nise faint resemblances to D. ferox ; the greater part even 

 more closely resembled D. Stramonium and D. quercifolia, with 

 which they had no more relationship than the species from 

 which they descended. Some had white flowers and green 

 stems, either self-coloured or tinted with purple at the base, 

 while others had violet flowers of various shades, and stems 

 more or less brown, sometimes even of a purplish black, as 

 deep as that of Z>. tatula, which is the most perfect type of the 

 violet group. The fruit was of all sizes, from that of a filbert 

 to that of a large walnut, and some of them were very spiny, 



* In hybrid Hellebores the same variable distribution of colouring mat- 

 ter is observable, also in the common Balsam ; and, as gardeners are well 

 aware, red or crimson varieties of Primula sinensis may be distinguished 

 from white-flowered plants by the colour of the petioles. 



