148 Plant-Breeding 



This explanation has also been applied to Cytisus hybrids 

 in which it has been shown that the epidermal tissues were 

 strikingly like those of C. purpureus, while the inner tissues 

 were like those of C. laburnum. 



In a later paper, Winkler arrives at the following 

 conclusions : 



Hybrids may be arranged in two groups, sexual and 

 graft-hybrids. The latter may be divided into three 

 classes according to the theoretical possibility of their 

 method of origin, viz. : (1) Fusion graft-hybrids arising 

 from a fusion of two somatic cells derived from distinct 

 species. (2) " Influenced " graft-hybrids which arise from 

 specific influences of one graft component upon the other 

 without cell fusion (as through chemical substances, trans- 

 location of cytoplasm, etc.). (3) Chimseras, in which 

 specifically pure cells from both graft components are 

 combined to form a new individual. These chimseras may 

 be : (a) Sectorial chimseras in which the two sorts of cells 

 in the growing point are divided by a longitudinal plane. 

 (6) Periclinal chimseras in which the periclinal cell layers 

 of the growing point are furnished respectively from one or 

 the other parent form, (c) Hyper-chimseras in which the 

 growing point is made up of a mosaic of cells derived from 

 the two parent forms. 



