112 D. P. Penhallow — Tendril Movements in 



the afternoon from 1.50 to 7.12 o'clock. If we now select those 

 figures under 1, 3, 5 b-c, 6 a-b, 8 b, and 9,* representing the 

 true maximum rate of motion in those tendrils for the entire 

 period of their activity, we will find that only one occurred 

 in the morning, all the others taking place in the afternoon be- 

 tween the hours of 1.50 and 6.50. 



Selecting an equal number of hours of day and night, making 

 the hours of division 7 a. m. and 7 P. M., we find that we obtain 

 a total length of diurnal movement of 1359 - 90 cm ; and of noc- 

 turnal movement of 536'90 om , thus making the latter in the 

 ratio of 1 : 2 "53 to the former, a difference which clearly indicates 

 that temperature exerts an influence far outweighing any retard- 

 ing effect upon growth which direct and bright sunlight may 

 have. 



This naturally brings up a question relative to the tempera- 

 ture at the time these figures were taken. The six figures 

 already selected as representing the maximum movements, were 

 found while the temperature ranged from 21*1° to 30 - 9° C. Of 

 these, the highest, viz: 6*5, 4*55 and 3"55 cm were found when 

 the temperature ranged from 24*4° C to 30 - 9° C; the other three 

 giving us 247, 2 '6 and 2 - 06 cm , were obtained between 214° and 

 28*3° C. We thus find that the more active of these waves 

 were formed under the influence of a temperature 3'8° C. higher 

 than that under which the less active were produced. We also 

 observe that while the more rapid movements are propagated 

 under medium temperature, the slower movements are devel- 

 oped under the extremes of temperature, some higher, some 

 lower. And yet again, that in the means of all the values of 

 each kind, the more rapid movements are developed under a 

 somewhat higher temperature than the slow movements, thus 

 indicating that while excess in either direction is detrimental, 

 higher temperatures are best adapted to the most rapid growth 

 so long as they fall within certain limits. 



Pursuing this line of thought yet a little further, and taking 

 the highest rate of each tendril movement — including, there- 

 fore, the six first considered — we find them obtained under an 

 average temperature of 27*2° C; while those waves of rapid 

 movement belonging to the same tendril, but of less amplitude, 

 were propagated under an average temperature of 24*8° C. Of 

 the thirteen maxima of movement obtained, one was found to 

 be coincident with the absolute maximum of temperature. 

 This, however, was a movement at the low rate of 0"85 cm per 

 minute. Three were found to occur on an increasing tempera- 

 ture, usually several hours before the maximum was reached ; 



* The remaining are not taken for the obvious reason that, as the tendrils to 

 which they belong were in the last stage of movement, they do not represent the 

 point now under consideration. 



