AUTOMATIC RECORD 209 



Irrigation. — There is, as is well known, a periodic varia- 

 tion of turgor which is disturbed by watering the plant at 

 irregular intervals. Precaution against this was taken by 

 placing the flower-pots containing the plants in a long 

 trough filled with water (sec fig. 119). The height of water 

 in the trough is maintained constant by a syphon. 



Vertical illumination. — The direction of sunlight changes 

 from morning to evening and the stem and leaves exhibit 

 appropriate movements under the changing direction of 

 hght. In order to obviate this, a special chamber was 

 constructed which allowed light from the sky to fall 

 vertically on the plant through a sheet of ground glass 

 which covered the roof, the light thereby becoming uniformly 

 diffused. The sides and the base of the chamber being 

 impervious to light, the plant was protected from side- 

 illumination. A narrow slit covered with red glass allowed 

 inspection of the curve during the process of record. 



The Ventilator. — A revolving ventilator, acted on by 

 the wind, sucked the air aw^ay from the chamber, thus 

 ensuring a constant supply of fresh air without causing 

 any disturbance of the record. 



Automatic Record of Diurnal Movement 



The Recorder. — The Oscillating Recorder employed is 

 of the quadruplex type carrying four recording levers 

 (fig. 119). The function of the apparatus is to record 

 various types of diurnal movement. The fourth lever records 

 the daily variation of temperature : the other three are 

 attached to plants of either the same or different species. 

 In the former case three records are obtained of the same 

 species of plant under identical external conditions. If they 

 agree in all essentials, the periodic curve may be taken 

 as characteristic of that particular species. A very great 

 saving of time is thus ensured, and it is therefore possible 

 to obtain characteristic curves of numbers of different 

 species of plants within the short period of a season. 

 The quadruplex recorder also permits the obtaining of 



