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 turgor, a contraction and a negative mechanical response.
2. Effect of Indirect stimulus is an increase of turgor, an expansion and a positive mechanical response.
3. Prolonged application of indirect stimulus of moderate intensity gives rise to a diphasic, positive mechanical response followed by the negative.
4. If the intervening tissue be highly conducting, the transmitted positive effect becomes masked by the predominant negative.
The laws of Effects of Direct and Indirect stimulus hold good not merely in the case of sensitive plants, but universally for all plants. This aspect of the subject will be treated in fuller detail in later Papers of this series.