Stout: A Graft-Chimera in the Apple 
ange which appeared in Florence, Italy 
about 1644. On some of its branches 
oranges are produced, on others citrons 
develop, and on other branches the 
fruits are part orange and part citron 
as shown en page 522 of Vol. 5 of this 
Journal (December, 1914). Another 
plant known as Cytisus Adami origin- 
ated in 1825 as a branch of a plant 
grown from a graft between Cylisus 
purpureus and Laburnum vulgare. 
Some branches of this plant are pure 
Cytisus purpureus, others are pure 
Laburnum vulgare, others are various 
mixtures of the two, and others bear 
leaves that are intermediate in charac- 
ter. Several types of plants are known 
which appear to be mixtures of the two 
species Crataegus monogyna and Mespi- 
lus germanica. All of these have been 
propagated vegetatively and have been 
objects of more than usual interest. 
How these plants originated has been 
a matter of no little discussion and 
speculation among botanists and horti- 
culturists. 
GRAFTING TO PRODUCE CHIMERAS 
The experimental production of 
chimeras in rather recent years has 
shown very clearly how such plants can 
arise incidentally through the practice 
of grafting. By a simple but ingenious 
arise incidentally through practice of 
grafting. By a simple but ingenious 
method of experimentation Dr. Wink- 
ler, now Director of the Botanical 
Garden at Hamburg, produced such 
plants under observation and control. 
He used the tomato and nightshade, 
two distinct and well-known species 
with marked differences in leaves, 
flowers and fruit. He made grafts, 
and when the scions were well estab- 
lished he decapitated the branches by 
cutting through the points of contact 
between scion and stock, thus exposing 
on the cut surface the two kinds of 
tissue and the lines of contact between 
them. On this surface a callus formed 
from which buds arose. If a bud arose 
entirely from the part that was night- 
shade the branch was nightshade only; 
if from tomato tissue the branch was 
pure tomato. If, however, a branch 
235 
arose over the line of juncture it was 
composed partly of tomato and partly 
of nightshade tissue. 
TWO KINDS OF CELLS IN SAME BRANCH 
Such branches were called ‘‘chime- 
ras." The simpler of these show 
vertical lines of differentiation; one 
sector bears the leaves, flowers, and 
fruits of the tomato while the rest of 
the branch bears those of the night- 
shade. Such branches and the plants 
grown from them by vegetative propa- 
gation are called ‘‘sectoral chimeras.” 
In such an association of two kinds of 
cells, each sort retains its own character 
and the leaves, flowers, and fruits of 
the two sectors are readily to be 
identified. 
Occasionally, however, branches 
arose which produced leaves, flowers 
and fruits that were intermediate or 
mixed in character. One of these 
(named Solanum tubingense) bears 
simple leaves like the nightshade but 
the leaves are more or less lobed and 
are hairy as the tomato. Another 
(Solanum proteus) resembles the to- 
mato more than the nightshade; the 
stems and leaves are hairy but the 
fruits are smaller than those of the 
tomato. Several types of intermediates 
were produced and for a time it was 
believed that these were true graft- 
hybrids resulting from the actual 
fusion of certain vegetative cells of the 
tomato and the nightshade in the 
region of contact in the graft. Later, 
however, a study of the internal and 
minute st.ucture of the cells in these 
plants revealed that the two kinds of 
cells characteristic of the tomato and 
the nightshade are both present, and 
that one kind exists as one or more 
continuous layers covering the other 
kind. It was found that Solanum 
tubingense has one outside or periclinal 
layer of tomato cells covering a core of 
nightshade tissue and that S. proteus 
has two such periclinal layers. Other 
types of the intermediates have one or 
more outermost layers of nightshade 
cells covering tissue of the tomato. 
The plants were thus found to be 
periclinal chimeras. A photo of four 
