224 



PLANT PHYSIOLOGY 



works are started and stopped by a cylindrical nut projecting from the 

 upper surface. It is to be wound, and not too tightly, once in two days, 

 which may be accomplished without disturbing the plant. Properly used 

 it will carry a 4-inch or smaller pot horizontally, or a larger size vertically. 

 As with all Klinostats, however, it revolves with the greater evenness the 

 smaller the weight it has to carry, and consequently the smallest pots allowed 

 by the subject under study should be used. The size with which the instru- 

 ment works best is the "three-inch," this size, however, being larger than 

 commonly supposed, since the measurements of pots are all internal. 



In using the Klinostat with plant vertical (Fig. 61), it should be levelled 

 by means of the extensible legs; a 4-inch flower-pot saucer should be stood 



Fig. 62. — Demonstration Klinostat arranged on special support stand; 



X». 



on the disc, into the rim of which it exactly fits, to catch the drip from 

 the pot, and the plant should be stood exactly in its center. In using 

 the Klinostat with plant horizontal, the general arrangement of figure 62, 

 where it is shown supported upon a special portable clamp stand, is advan- 

 tageous, though any upright support may be used if firm enough to hold 

 the Klinostat in a truly vertical position. The weight of the plant must 

 be centered in order that the instrument may be able to keep the revolution 

 uniform throughout. This adjustment is effected thus: The pot is attached 

 to the disc by means of the screw-rods, which, however, are not tightened. 

 The plant with the spindle-arm is then placed in position, resting on the 

 extensible spindle-rod support, as shown in the figure, but the screw attach- 

 ing the spindle-arm to the clockwork is left loose. The plant is then given 

 a twirl with' the hand, and after turning once or twice comes to rest with 

 its heaviest side down. The pot is now pushed on the disc from the heavy 

 side and twirled again, and the process is repeated until, after a few trials, 

 th; plant comes to rest indifferently in any position. Then the screw-rods, 



