Hybridization 147 



shape of the leaves and the color and type of the flowers 

 between the nightshade and the tomato. The fruit is 

 very much like that of the nightshade, but is rather larger, 

 and although it is black there are some traces of the red 

 or yellow color of the tomato. 



2. Solanum proteus has very variable leaves, which, 

 on the whole, are more divided than those of S. tubingense, 

 while in the characters of the flowers and the fruit it is 

 more like the tomato than like the nightshade. 



3. Solanum Kolreuterianum, and 



4. Solanum Gartnerianum. These forms have been 

 produced several times. The first is more like the tomato, 

 the second more like the nightshade, but each differs in 

 important particulars from either of the parents. 



5. Solanum Darwinianum. The point of especial inter- 

 est in connection with this form is that of all the so-called 

 " graft-hybrids " secured by Winkler this seems to be the 

 only one which is likely to prove a hybrid in the strict 

 sense of the word. The fruit of this plant, unlike the 

 others, was sterile, no perfect seeds being formed. The 

 fruit itself is a round small berry like the fruit of the night- 

 shade in form, but having the color and structure of the 

 tomato. 



Are these real graft-hybrids ? In all of these forms when 

 seed was produced at all, it produced seedlings of one parent 

 or the other, never producing the apparent hybrid. 



It has been suggested by Bauer that these apparent 

 true hybrids might be chimaeras of a type which he has 

 called "periclinal," i.e. the outer tissues are derived 

 from one parent, and the inner tissues from the other, 

 but none of the tissues themselves are of hybrid origin. 



