GRAFT-HYBRIDS. 569 



would be easy to find 100 blossoms with corollas differing from one another in the 

 distribution of their colours and in the arrangements of the spots and streaks upon 

 them. Similar phenomena are exhibited by Iris pumila and Polygala amarella. 

 The flowers in Polygala amarella are equally blue and white or sprinkled with 

 blue and white, and it is also no rare thing for plants to bear white flowers 

 interspersed with a few which are sprinkled with blue. In the same way several 

 species of Anthyttis, Euphrasia, Galeopsis, Linaria, Melittis, Ophrys, Orchis, 

 Saxifraga, &c., exhibit considerable variation in the colours and markings of their 

 petals, which yet is not to be attributed either to hybridization or to the influence 

 of soil or climate. Reference must also be made here to the large number of species 

 (already mentioned on p. 194) in which the floral coloration is by turns blue and 

 white, red and white, blue and red, yellow and white, and so on. Heterochromatism, 

 i.e. the change in the coloration and marking of petals, serves, in fact, in some 

 plants as a specific character. Contrasting with these heterochromatic species are 

 those with homochromatic flowers, which, as far as experience has shown, invari- 

 ably present the same colour and pattern, and only exhibit a slight variation in the 

 depth of the colour when subjected to the influence of light of varying degrees of 

 intensity. Iris Kochii and I. Florentina, Primula Auricula, and P. hirsuta, 

 together with other pairs of species referred to above as the progenitors of hybrids 

 of special interest, belong to the category of plants possessing homochromatic flowers, 

 and it is obvious that in the hybrid offspring of such plants the floral coloration 

 would be an important sign of identity. 



This will be the most convenient place in which to introduce a few words 

 concerning the Bizzaria of Italian gardeners, and also concerning so-called graft- 

 hybrids. The name of Bizzaria has been given by the Italians to an extremely 

 curious Orange. Gallesio (1839) states that this Orange-tree produces at the same 

 time foliage, flowers, and fruit identical with the Bitter Orange (Citrus Aurantium) 

 and with the Citron of Florence (Citrus medica), and likewise compound fruit, 

 with the two kinds either blended together, both externally and internally, or 

 segregated in various ways. In the fruits of the Bizzaria which I have seen, five 

 longitudinal stripes of the colour of a Citron were interpolated in the fruit of the 

 Orange. Other fruits were, on the whole, like Oranges, excepting as regarded an 

 eighth of their mass, which in form, colour, and taste resembled a Citron, and was 

 also peculiar for its extreme convexity. This anomalous segment stretched in the 

 form of a light-coloured cushion from one pole of the spherical fruit to the other. 

 Growers maintain that the Bizzaria is the result of a cross between Citrus medica 

 and Citrus Aurantium, though the gardener who, in 1644, in Florence, raised this 

 tree, declared it was a seedling which had been grafted, and after the graft had 

 perished the stock sprouted and produced the Bizzaria (according to which 

 account it would be a graft-hybrid). In other similar cases of Citrus hybrids, how- 

 ever, such as the Bergamot Orange, aUeged to be a hybrid of the ordinary Lemon 

 and the Bitter Orange, one finds the characteristics of the parent-species do not 



