PREVENTION AND CURE. | 61 
tendency for the callus to form anywhere except in the intervening 
-spaces. When the pieces are more or less imperfectly fitted and are 
not firmly held together, especially at the lower end of the scion, there 
is a tendency for the callus to grow out into the air, forming thick 
cushions (Pl. VIII, fig. 2) or gall-like outgrowths. The wrappings 
were planned to confine this formation of callous and to hasten the 
union between scion and root pieces. 
In order to find a method of controlling the formation of callus, 
25,200 root grafts were wrapped with various materials (Pl. VIII, 
fig. 1) during the winter of 1904-5. The idea of wrapping root 
erafts is not a new one, since nurserymen used both waxed cloth and 
waxed paper for many years before the present method of thread 
wrapping came into vogue. 
All of the grafts made for the experiment were of the type known 
as “whip” or ‘‘tongue”’ grafts. They were especially well made 
from No. 1 Kansas roots, fitted with a selected lot of scions from 
each of the following varieties: Winesap, York Imperial, Wealthy, 
Missouri, and Northern Spy. They were made in February, packed 
in moist, chopped excelsior, and stored in a cool place for about six 
weeks. 
The manner in which the wrapping was made and the material 
used may be briefly described as follows: 
Wrapping with cloth—The cloth used was a cheap black calico of 
the poorest grade obtainable in the market. (See Pl. VIII, fig. 1, C.) 
This was torn into strips 1 inch wide and 4 or 5 inches long. After 
the graft was made one end of the cloth was dipped for one-half inch 
into hot, melted grafting wax. Starting with the other end, the 
cloth was then wrapped tightly around the scion and the free waxed 
end pressed down. This completed the operation. 
Wrapping with rubber—The rubber used was of a quality similar 
to dental rubber, which is also frequently used for insulating wires. 
(See Pl. VIII, fig. 1, #.) It was bought in rolls 1 inch wide and was 
cut off in such lengths as were necessary to completely envelop the 
union. The rubber was usually wrapped so as to encircle the union 
twice, and the free end was fastened with rubber cement applied 
with a brush. 
Wrapping with waxed paper.—Sheets of ordinary unglazed printers’ 
paper were waxed on one side by coating them with hot grafting wax 
applied with a paint brush. (See Pl. VIII, fig. 1, G.) They were 
then cut into I-inch strips, ten to twenty sheets being cut at one 
time, and these again into strips about 4 or 5 inches long. One paper 
strip was then wrapped around the union, the waxed side toward the 
graft, the free end being stuck down by pressing on it. 
Wrapping with plain thread—The thread used for the ordinary 
erafts was machine cotton No. 9. (See Pl. VIII, fig. 1, A.) 
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