222 



PLANT PHYSIOLOGY 



by which gravitation is felt equally from all sides, as occurs when the 

 object is continuously rotated in a vertical plane. 



EXPERIMENT. To the rim of the disc of a klinostat revolving in 

 a moist -chamber, fasten 5 or 6 corks after the manner shown in fig- 

 ure 60. To each of these pin a soaked seed of the kind used in the 

 foregoing experiment, placing between seed and cork a short piece 

 of cotton wicking arranged to dip at each revolution into a dish of 

 water, thus keeping the seeds wet. Observe the growing parts and 

 ascertain the determinants of the positions taken. 



A large flower-pot, standing in a saucer of water and covered by another 

 water-containing saucer, makes an ideal moist-chamber for this purpose. 

 A hole for the klinostat rod may easily be drilled 

 by a file turned in a carpenter's brace. The 

 water may be supplied by stopping the hole in 

 the bottom of the pot and filling it to the 

 desired depth. 



KLINOSTATS (OR CLINOSTATS). The Klino- 

 stat is an indispensable instrument for any 

 thorough work not only upon geotropism, but 

 also upon other phases of the irritability of 

 plants. The requisites of a good Klinostat 

 are: (a) it should carry plants of considerable 

 weight; (6) should carry them either horizon- 

 tally, vertically, or at any intermediate angle; 

 (c) should revolve completely (preferably at a 

 speed variable at will), not faster than once a 

 minute or slower than once in thirty minutes 

 (this time bringing the revolution within the 

 reaction time of a responding structure without 

 introducing centrifugal force); and (d) should 

 revolve uniformly even with somewhat irregu- 

 larly balanced load, the uniformity being im- 

 portant since any regularly recurring retardation 

 permits a summation of stimuli, with their 



appropriate response, in that position. The 



| original Klinostat invented by SACHS in 1872 



FIG. 60. ARRANGEMENT FOR was driven b ? a weight-and-pendulum clock, 

 KEVOLVING SEEDLINGS BY and carried but H g ht loads - The standard 

 THE KLINOSTAT- Xi instrument of recent years has been PFEF- 



Particulars iri text. FER ' S Qff 1 * in his "Physiology," 3 , 169), 



which is supplied by Albrecht of Tubingen 



at a cost of 350 marks. It is driven by a powerful spring controlled by a 

 fan governor, and depends upon accurate balancing of the load to ensure 

 uniformity of revolution. Similar in principle, though very different in 

 details of construction, is the WORTMANN Klinostat (pictured in DETMER, 

 455)) supplied by Ungerer Bros, of Strasburg at a cost of about 200 marks. 



