thorn-medlar and several freak apple trees. The first of these is 
said to have originated near Florence, Italy, about lt>44, from the 
point of union in a graft between the orange and the citron. 
Some branches of this freak plant bore oranges, other branches 
bore citrons, while still other branches bore fruits part orange 
and part citron. 
The apples illustrated in figure 2 came from a tree in Nova 
Scotia, said to have originated from grafting together two varie- 
ties having differently colored fruits. Some apples on the tree 
are said to be like those from the scion, others are like the fruit 
the stock bore, while still other fruits represent a union of both 
varieties. The line of color demarcation is clearly shown in the 
photograph. When these mixed fruits were examined internally, 
each part had the characteristic flavor and texture of the variety 
to which its external color characters assigned it. 
But it is from Dr. Winkler’s careful work that the explanation 
of this phenomenon eventually came. Winkler’s graft-hybrids or 
chimeras, as they are now more accurately called, were found to 
to be of four kinds, only one of which was truly a graft-hybrid, 
produced through the union of two cells. The other varieties are 
known as sectorial and periclinal chimeras, and all, including 
the true graft-hybrid, were produced through reciprocal graft- 
ing of scions and stocks of the tomato and nightshade. Cleft, 
saddle and splice grafts were made between these two mark- 
edly distinct forms, and as soon as the union between scion 
and stock was well established, a horizontal cut was made 
through the graft union, exposing the cut surface of both scion 
and stock tissue. When this surface healed over, buds arose. 
Those buds arising from either nightshade or tomato tissue re- 
sulted in pure nightshade or tomato branches, but those buds 
originating along the cut surfaces where scion and stock came 
together gave rise to chimeras and contained both nightshade 
and tomato tissue. Each tissue retained its own individuality, so 
that the product of such a union was a joint partnership of which 
hundreds of cells were nightshade and hundreds were tomato. 
There were no cells part nightshade and part tomato, except in 
the case of the true graft-hybrid mentioned earlier. In the sec- 
torial or the simplest form of chimera, the respective areas of 
nightshade and tomato tissue were arranged in vertical planes, 
one side of the branch being pure nightshade, the other side pure 
tomato. Leaves arising from the boundary line between the two 
tissue areas were part nightshade and part tomato. Stems of 
such plants in cross section, showed areas of both sorts of tissue. 
