The Editor: Plant Chimeras 



527 



green tissue in the terminal bud over- 

 laid by a layer or two of white cells. 

 Now if a branch starts out just at this 

 point where the green cells have been 

 overlaid by white, it will start from and 

 with green tissue, but it will have to 

 make its way through this skin of white 

 cells, and will take them along with it 

 as its own outer tissue. As the branch 

 grows, the white cells grow along with 

 it on its surface, still retaining their 

 connection with their parent white 

 tissue, while the larger part of the branch 

 — namely, all the interior part — is 

 made of the green tissue. So when the 

 branch finally attains its full size it 

 might be described, figuratively, as con- 

 sisting of a white branch and leaves, 

 hollow, into which a green branch and 

 leaves of the same shape but a little 

 smaller have been thrust up. In other 

 words, it is a hand in a glove. Most of 

 each leaf appears green, because the 

 thin layer of white cells is underlaid by 

 so much green tissue that shows 

 through; but at the edges of the leaves 

 the green cells were crowded back, the 

 white cells hold undisputed possession, 

 and no green is to be seen, the result 

 being the white edge around the pe- 

 riphery of the leaf. Because of this 

 peripheral distribution of the white 

 cells, Baur called such chimeras peri- 

 clinal, to distinguish them from the 

 sectorial chimeras which both he and 

 Winkler had produced in the earlier 

 stages of their experiments. 



THE SOLANUM CHIMERAS. 



It was at once suggested that Wink- 

 ler's later chimeras — those of the blended 

 or intermediate type, which he himself 

 had never been able satisfactorily to 

 explain — were periclinal chimeras. He 

 made a careful examination of them on 

 this hypothesis, and reported that such 

 was the fact. In Solanum tubingense 

 and 5. proteus, he found that the entire 

 body of the plant, consisting of night- 

 shade, was overlaid by a film of tomato 

 tissue, in the former case consisting of 

 only one layer of tomato cells, and in 

 the latter case of two. Solanum 

 gaertnerianum and 5. koelreuterianunt 

 were found to be tomato at heart, but 

 wholly clad in a skin of nightshade, the 



SIMPLE GRAFT 



This illustrates the simplest form of graft — 

 a split, cleft or wedge graft. Of the 

 two plants thus united, the lower one, 

 which furnishes the root system, is 

 called the stock; the upper one, which 

 furnishes the branches of the developed 

 plant, is known as the scion. When 

 the scion is inserted in the stock, as 

 here shown, and the graft bound up, 

 callus tissue forms at all the points of 

 juncture. To produce chimeras the 

 whole graft, after it has "taken," is 

 cut in two along the line shown, so 

 that the cut surface on top includes 

 parts of both stock and scion; more 

 callus forms on this top plane and gives 

 rise to sprouts which, in favorable 

 cases, show the characters of both 

 parents. Enlarged eight diameters. 

 (Fig. 5.) 



