146 Plant-Breeding 



Winkler's Solatium graft-hybrids. Professor H. Winkler 

 of Tubingen has carefully performed experiments in 

 making graft-hybrids with the black nightshade, Solanum 

 nigrum, and two varieties of the tomato, Solanum lyco- 

 persicum. These two species are very distinct, and indeed 

 many botanists regard the tomato as belonging to a dis- 

 tinct genus lycopersicum, so that Winkler's graft-hybrids 

 may be regarded as bigeneric hybrids. Seedlings of each 

 were grown and reciprocal grafts made. The graft and 

 stock united readily whether the nightshade or the tomato 

 was used as the stock. 



Naturally the majority of the shoots arising from the 

 cut surface of the stem were either pure nightshade or 

 pure tomato. But finally shoots were observed which 

 were evidently of mixed origin. The first of these graft- 

 hybrids were obviously composed of pure elements 

 derived from the two parents. Some of these shoots were 

 almost equally divided by a median line, on one side of 

 which the organs stem, leaf were those of the night- 

 shade, while on the other the organs were evidently derived 

 from the tomato. It is obvious that such unusual forms, 

 which Winkler called "Chimaera," are not hybrids in any 

 true sense of the word, but have arisen from buds which 

 contain the tissue of the two parent formed at the junction 

 of the stock and graft. 



Later on there developed, however, shoots which were 

 evidently of hybrid origin. Cell fusion had unquestion- 

 ably taken place. Several hybrids with different attributes 

 were produced. These have been given different names 

 by Professor Winkler, and may be described as follows : 



1. Solanum tubingense is intermediate in the size and 



