The Editor: Plant Chimeras 



529 



1. 



2. 



TWO FORMS OF CHIMERAS 



Diagram after Baur showing the difference between sectorial and periclinal chimeras, as 

 exhibited in the terminal bud. The bud at the left (No. 1) may be taken to represent a 

 periclinal chimera between a white plant and a green plant; the green tissue is entirely 

 overlaid with a layer of white cells, so that any branch sent out from the green tissue 

 must of necessity pass through and carry with it white cells as an outer skin. At the 

 right (No. 2) is the bud of a sectorial chimera between white and green plants, where the 

 two kinds of tissue exist side by side and come in contact only in one plane. Obviously, 

 any branch sent out from the green tissue will be green, any branch sent out from the 

 white side will be white. It is only a branch arising exactly on the line of juncture of 

 the two kinds of tissue that may be expected to carry both kinds of cells and thus form 

 a sectorial chimera. (Fig. 7.) 



latter sort of cells being two layers deep 

 in 5. gaertnerianum, while 5. koelreuter- 

 ianum had but one layer. 



As soon as it was understood what 

 this kind of graft -hybridization really 

 meant, attention at once reverted, of 

 course, to the classic specimens. Cytisus 

 adanii was found to be a laburnum in 

 disguise, so to speak — a laburnum with 

 the skin of a purple broom. Baur 

 demonstrated that the Crataego-mes- 

 pilus was also a periclinal chimera, its 

 epidermis being derived from the medlar 

 and its interior from the whitethorn. 

 By common consent, the Bizarria was 

 separated from these and put in the 

 class of sectorial chimeras. 



Since then many other chimeras, be- 

 longing to one or other of these two 

 classes, have been produced, or have 

 been found in nature, particularly in 

 such variegated plants as Coleus.^ One 

 of the most recent was produced by 

 grafting a peach on an almond. The 



An Apple Chimera. 



first crop borne consisted of true 

 peaches, but in the next year the tree 

 produced buds some of which resembled 

 those of an almond, while others were 

 like peach buds and others again were 

 intermediate. Seeds from the graft 

 produced trees which in foliage resem- 

 bled both the parents. An apparent 

 chimera made of two varieties of 

 rhododendron was produced by grafting 

 Madame Linden on Cunningham's 

 White. "A shoot which had been left 

 on the stock just below the graft pro- 

 duced pale rosy-lilac flowers; whereas 

 the flowers of the stock are white, and 

 those of the scion deep rosy-lilac with 

 dark red spots. The form of leaf borne 

 by the anomalous shoot is also distinct, 

 approaching that of the scion."* If 

 more horticulturists would make the 

 attempt, it is probable that the number 

 of chimeras reported would be very 

 large. Winkler has pointed out^ num- 

 JouRNAL OF Heredity, V, 5, pp. 200-202, 



3 See also Castle, W. E. 

 Washington, May, 1914. 



* Revue Horticole, Paris, August 1, 1913, and vSeptember 1, 1913; abstract in Gardeners 

 Chronicle, London, May 16, 1914. 



* Die Chimarenforschtmg als Methode der experimentellen Biologic, in Sitzungsberichten der 

 phys.-med. Ges. zu Wiirzburg, 1913. For the original reports of his work, see Winkler, Hans. 

 Ueber Pfropfbastarde u. pflanzliche Chimaren, Ber. d. deutsch. Botan. Ges., 25, 568, 1907; 

 same SiVithor , Sokinum Tuhingense, ein echter Pfropfbastard zwischen Tomate u. Nachtschatten, 

 ibid., 26, 595, 1908; and the same journal, passim, during those and the following years, for the 

 views of the leading German botanists on the whole subject. The files of the Gardeners' Chronicle 

 (London) may also be consulted with profit by those interested in graft -hybrids. 



