60 PENHALLOW ON MECHANISM 
standing at 21°C. The times of least movement were found to extend from 4.35 to 5.30, 
and again from 7 to 8.30 p.m., when the observations ceased. 
At the commencement of observations, the sun was shining brightly, and the effects 
were sufficiently strong to cause a depression of all the leaves and flowers. Shortly after 
observations ceased, the sky became cloudy, and at 9 o’clock there was a heavy shower 
which revived the whole plant, and once more brought all the parts into active condition. 
The first movement recorded, was to the left, action in that direction predominating 
during the entire period of observation. The total movement to the right was 18.80 c.m.; 
to the left 88.8 cm.; and the ratio, therefore, as 1: 4.72. 
Tendril No. 5 b, c.—This represents the same as the preceding tendril, observations 
upon which were interrupted Aug. 13th at 8 p.m., and resumed the next morning (14th) 
at 8 o'clock, being continued through the 14th and 15th. During the night, the arm was 
quite active, and in the morning showed no tendency whatever to discontinue its nuta- 
tions. From the time indicated, observations were continued for twenty-four consecutive 
hours. The entire distance travelled during that time was 511-7 cm., thus giving an 
average rate of 0.37 cm. each minute. 5 b-c. indicates a change of paper, which occurred at 
6.20 p.m., at a time when the tip had dropped to the ground, where it remained without 
change of position until 8.35 p.m., when its nutations were resumed. 
The time of most rapid movement, was during the two minutes from 4.55 to 4.57 
p-m., on a decreasing temperature, and five hours after the maximum wave had passed. 
The rate of movement was 4.55 cm. per minute, the times of most rapid movement 
occurring from 8 to 10.20 a.m.; 1.30 to 2 p.m.; 4 to 5.30 p.m., and 10.53 to 11.05 p.m.; the 
maximum of these being from 4 to 5.30 pm. The absolute minimum of motion occurred 
from 4 to 5.04 a.m., when the tip traveled at the rate of 0.043 cm. per minute, this being 
at a time of low temperature. The times of least activity were from 10.20 am. to 1.30 
p.m.; 2 to 4 p.m.; 5.30 to 10.53 p.m.; and from 11.05 during the remainder of the night, 
and until the end of the experiment at 7 o’clock in the morning. In these observa- 
tions, there appears a very sharp division at 5.30 p.m., between the waves of more rapid 
diurnal, and those of slower nocturnal movement. 
The experiment commenced with very pleasant weather and all parts of the plant in 
vigorous condition—the leaves being erect and the flowers open. From 12 m. to 4 p.m., 
the leaves were drooping and the activity of the plant small. This, with the exception 
of one-half hour from 1.30 io 2 p.m., was a time of slow movement. At 4 o’clock p.m., 
the leaves began to resume their normal, fresh appearance and so continued until the 
close of observations. Towards morning, a very heavy fog gathered and reached its 
maximum at four o'clock, the time of minimum motion. 
Sinistrorse movement was first noticed. The entire dextrorse motion was 282.1 cm.; 
the sinistrorse 229.6, and the ratio 1:0.81, thus showing a greater tendency to equality 
than previously observed. 
The figure described during the movement of this tendril—reduced to one-half the 
actual size—is shown in Plate III, the position of the observer corresponding to the base of 
the tendril. The following table relating to these movements will convey a fairly accu- 
rate idea of the general features of circumnutation with reference to time and distance :— 
