GRAFT-HYBRIDS AND OTHER CHIMERAS 



375 



first type is termed sectorial and the second periclinal. A third type 

 has been recognized by Winkler in which the vegetative cone is a mosaic 

 of unlike cells. This type he named hyperchimera. Coit has reported 

 the case of a Valencia orange tree which from its consistent instability 

 appears to have been propagated from a mixed bud and hence belongs in 

 this class of chimeras. 



All of Winkler's Solanum chimeras are periclinal and the degree of 

 resemblance of such a graft-symbiont to the parent whose tissue comprises 

 the inner portion of the shoot seems to depend upon the number of layers 

 of cells from the other parent which envelop it. Thus the form lubigense 



A B 



FIG. 151. Winkler's Solanum chimeras. Produced by grafting tomato on nightshade 

 (and vice versa). From left to right, Solanum Gaerlnerianum, S. Koelreulerianum, S. 

 proteus, and S. tubigense. The second resembles the tomato parent most closely; it has a 

 tomato body with nightshade epidermis (a single layer of cells). The fourth is most like the 

 nightshade parent and it has a nightshade body with tomato epidermis. The first has a 

 tomato body covered with 2 layers of nightshade cells and the third, a nightshade body 

 covered with two layers of tomato cells. Such combinations are called periclinal chimeras. 

 (From Journal of Heredity.) 



(Fig. 151, D) which closely resembles the nightshade has all the inner 

 portion of S. nigrum, with just an epidermal layer, one cell thick, of S. 

 ly coper sicum. But proteus (Fig. 151, C), whose leaves are much more 

 like tomato leaves, has a double layer of tomato cells overlying the 

 nightshade body. Similarly, Koelreuterianum (Fig. 151, B) is really a 

 tomato with nightshade epidermis, while Gcertnerianum has a tomato 

 body covered with two layers of nightshade cells. These graft-hybrids 

 were discovered only after much patient work in the course of which 

 Winkler made 268 grafts which produced more than 3000 shoots. All 

 four were propagated from cuttings and by this method they have been 

 obtained and grown by the New York Botanical Garden. 



It has not been possible to compare these forms with true sexual 

 hybrids because no one has yet succeeded in crossing the tomato and the 



