diminution of distance gives rise to ii resultant negative response, the positive being masked by the predominant negative.
From what lias been said it will be understood that the exhibition of positive response is favoured by the con- ditions, that the transmitting tissue should be semi-conduct- ing, and the stimulus feeble. It is thus easier to ex- hibit the positive effect with the feebly conducting petiole of Avenhoa than with the better conducting petiole of Mimosa. It is, however, possible to obtain positive response in the Mimosa by application of indirect stimulus to the stem in which conduction is less rapid than in the petioles.
TABLE IX. — PERIODS OF TKANS.MISSION OF rO.SniVE AND NEUATIVE IMPULSES IN THE PETIOLE OF AVEHRHOA AND STEM OF MIMOSA-
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No.
1 2 3 4 5 6 7 « 9 10
Specimen.
Distance in
mm.
Stimulus.
Transmission
period for
positive
impulse.
Transmission
period for
negative
impulse.
Averi-iioa ...
)) J)
» ihimosa ...
»
70
130
10
20
35
5
10
20
60
35
Thermal
Induction-.shock
Chemical Induction-shock
>) ))
Chemical
22 sees.
40 „ t) „
1^ „
21 „ 0-5 „ 0-6 ,, 11 ., 2 „ „
65 aecs.
95 „
20 „
48 „
50 „
12 „
9--1 „ 1 10
29 „ 17 „
EFFECTS OF DIRECT AND INDIRECT STIMULUS.
From the results given in course of the Paper we are able to formulate the following laws about the effects of Direct and Indirect Stimulus on pulvinated organs : —
1. Effect of all forms of Direct stimulus is a diminution of
tlrgob, a contraction an'd a negative mechanical response.
2. Effect of Indirect stimulus is an increase of iurgor, an
expansion and a positive mechanical response.
