2 I 2 
Notes on Recent Literature. 
Graft-Hybrids. 
HE classical cases which have been cited as examples of graft- 
1 hybrids 1 are well known to everyone. These intermediate or 
hybrid types, described as being of vegetative origin, had, however, 
only been produced in rare and isolated cases, and none of the 
persistent attempts to secure a repetition of the phenomenon had 
met with any success. The nature of these forms and the manner 
of their origin therefore provided a fertile field for debate, which, 
however, was productive of little positive result. 
But within the last two or three years notable progress has 
been made towards a solution of the problems of graft-hybridism. 
The starting point was Winkler’s success in inducing the development 
of graft-hybrids between the Tomato and the Black Nightshade. 
Winkler 2 found in Solanum a genus of plants which, under 
suitable treatment, very readily produce adventitious shoots Not 
only so, but the development of these shoots can be localized at a 
desired point. Reciprocal grafts were made between seedlings of 
the Tomato and the Nightshade. The grafts having been given 
time to become established, the plants were cut through transversely 
in such a way as to expose the newly joined tissues of scion and 
stock at the cut surface. 
Adventitious shoots developed from the callus formed over the 
cut surface. The majority of these shoots had their origin in 
tissue belonging entirely either to the scion or to the stock. Such 
shoots merely reproduce the pure species from whose tissue they 
originated. But other shoots had their origin exactly upon the line 
of junction between the tissues of the two graft-symbionts; in such 
shoots the characters of the two species are combined in various 
ways. 
In the simplest case 3 , the tissues of the two graft-symbionts 
are united side by side so as to build up a single shoot, of which 
one side is pure Tomato, the other pure Nightshade. The contrast 
between the stiff hairs and divided leaves of the Tomato and the 
almost glabrous, simple-leaved Nightshade gives these “ sectorial 
chimaeras ” a sufficiently striking appearance. 
But in addition to the sectorial chimaeras, Winkler 4 also 
obtained adventitious shoots which were intermediate in general 
habit between the two pure species. In all five, distinct intermediate 
types have now been obtained, each representing a different 
combination of the characters of the Tomato and the Nightshade, 
In general character and behaviour, these types are exactly 
1 See Darwin (6), Strasburger (10), Noll (8). With regard to 
Darwin’s cases of the transference of chlorosis through 
grafting, see Baur, “ Uber infektiose Chlorosen, etc.,” Ber. 
d. Deutsch. Bot. Gesell., XXV., p. 410. 
2 Winkler (11). 
3 Winkler (11). 
< Winkler (12) and (13). 
