106 D. P. Penliallow — Tendril Movements in 



retardation toward the latter hour. These waves were coinci- 

 dent with the greatest heat wave, the greatest retardation of 

 motion occurring after the maximum of heat had passed. 



The experiment commenced with the sky clear and the plant 

 in an active condition. As the heat increased, however, its 

 effects upon the plant were noticed, and at 12 o'clock, with 

 the thermometer at 34*1° C, the leaves drooped and the whole 

 plant was in a very flaccid condition. During this time the 

 waves of slowest motion occurred. This condition continued 

 until, with considerable fall in temperature during the after- 

 noon, the normal tension and activity of the plant were restored, 

 when the waves of greatest movement were noticed. The entire 

 dextrorse movement of the tendril was 92*90 cm , the sinistrorse 

 134-20 cm , and the ratio was, therefore, as 1 : 1.44. 



No. 7b. — This was the same as the preceding, observations 

 upon which were discontinued during the night, but resumed 

 on the morning of the 17th at 8 A. M., and carried over a period 

 of seven hours and fifty minutes. The entire movement during 

 this time was 94'40 om , giving an average rate per minute of 

 0"205 cm . Most rapid movement was at the rate of 0*555 cm 

 per minute, and occurred from 8 to 8.15 A. M., at the very com- 

 mencement of observations and on a rising temperature, six 

 hours before the maximum was reached. The waves of most 

 rapid motion were found from 8 to 11.30 A. M. Least move- 

 ment took place at 1.30 to 2 p. m., at the rate of 0'08 cm per 

 minute. This was just at the time of maximum temperature. 

 The waves of least motion were found from 11.30 A. M. to the 

 close of observations at 3.40 P. M., coincident with a rising and 

 maximum temperature. 



Observations commenced with moderate temperature, clear 

 sky and an active condition of the plant, continuing thus dur- 

 ing the time of greatest movement until, at 11 o'clock, the 

 leaves became depressed from the effects of heat, and from 

 11.30 on, the waves of slow motion were found. At 12 M. the 

 sky was overcast and the air loaded with moisture. At 1 P. M. 

 the leaves were restored to their normal condition and erect 

 position. At the same hour rain commenced and continued 

 during the remainder of the experiment. 



The total movement to the right was 25 -10 cnl ; to the left 

 69 ^O™, and the ratio was, therefore, as 1 to 2*76. 



Tendril No. 8. 



No. 8a. — This filament was selected August 16th at 9 A. M. 

 The time of observation covered a period of nine hours and 

 fifty minutes, or until 6.50 P. M. The entire movement during 

 this time was 314 , 50 cm , giving an average rate per minute of 

 0"516 cm . The time of greatest movement was from 3 to 3.15 



