462 BROOKLYN BOTANIC GARDEN MEMOIRS 
value of the various methods employed in inducing responses to con- 
tact stimulation. Deductions, however, based upon a large series of 
experiments not included here justify us in stating that surrounding 
plants loosely and irregularly with twine does not produce the same 
degree of stimulation or response, as by the more thorough contact 
derived from the use of other material such as wire netting with a 
uniform mesh, or, in other words, plants react more pronouncedly to a 
larger contact surface than to a relatively smaller one, although there 
probably exists a definite size of mesh which would produce the best 
result, and this would undoubtedly vary with different species. There 
appears, however, to exist some difference in the degree of stimulation 
arising from the same size mesh, as shown by the behavior of some 
species when the contact is applied to the leaves. The leaves, for 
example, of the sunflower and corn do not respond so freely as those of 
tomatoes and the castor bean presumably because the leaf apices 
are the most sensitive as in the case of tendrils. The latter species, 
possessing different type leaves, would appear to act differently on this 
account. 
TABLE 5 
Showing Growth of Castor Bean (Ricinus communis L.) in Contact with Wire Netting’ 
Average Dimension and Weight in Centimeters and Grams 
Internodes | | Percentage Gain i 
| | } | ie ia l Per ain in 
| Height | Diameter Stem | Wake | on | Weight | Height by Contact 
| 
Normail:.5...- =.) 32-3 rae <= ly eto |e ih gee 
Contact wire...| 55.1 1.18 IS rES Ie 426 200 70% 
The data derived from these experiments are not sufficient to allow 
of deductions being drawn which would be of any value in determining 
the relative value of the various-sized meshes in stimulating growth. 
In some cases where galvanized iron netting with a one-inch mesh was 
employed, the stimulation appeared to be equally as great as with the 
two-inch mesh. Neither is it possible by these tests to determine 
accurately the difference in the degree of stimulation which resulted 
from the use of wires and that from the contact of the plants them- 
selves. In all cases where single plants were employed they were 
removed far enough away from one another so as not to touch. The 
stimulated growth, therefore, was due entirely to the material which 
surrounded them. On the other hand when plants were grown in 
such a manner as to touch one another there existed two sources of 
contact. In the experiment shown in Table 9, six sunflower plants 
572 plants used. Plants in pairs. 
