Page:Researches on Irritability of Plants.djvu/98

complete, and the subsequent fatigue is less than after the first response. Therefore the fourth response, though small, is not so small as the second. Thus while the first, third, and odd series of responses are progressively diminishing from a maximum, the even series—second, fourth, and so on—are increasing from a minimum. In this way the difference between the successive responses is tending to disappear, a process which is practically complete in the seventh and eighth, after which uniformity is attained. It is very interesting to note that the sum of heights of each pair of responses is approximately the same for successive pairs, and the height of a response in the uniform series is not appreciably different from the mean of the maximum and minimum of the preceding pairs, as will be seen from the following table:—

Table giving Heights of Successive Responses

Number.

Height of response.

Mean of successive pair.

 
(1)..
(2)..

mm. 30 8

$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$

mm.

19

 
(3)..
(4)..

26 12·5

$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$

mm.

19·2

 
(5)..
(6)..

18·5 17·5

$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$

mm.

18

 
(7)..
(8)..

17·5 17·5

$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$

mm.

17·2

In this adjustment to uniformity we are able to watch a tuning of the organ, as it were, its gradual accommodation to the stimulus impinging upon it. Uniform responses may