DAILY PERIODICITY OF GROWTH IN LENGTH, 
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pot, the thread passing vertically over an easily moveable pulley and moving an index 
fixed to the free end of the thread or to the pulley. . u ^ 
I. The rhread-indicator is a simple contrivance in which the free end of the thread 
Fig 48i.-Auto,?raphic Auxanometer, for recording the growth in length during short periods of an internode of a 
growing plant/; s s' the Hnes scored by the index 2 on the blackened paper/ fixed to the cylinder C which is made to 
rotate eccentrically by means of the clock-work D. 
which hangs down from the pulley and is kept tight by a weight of a few grammes 
carries a horizontal needle which moves freely over a graduated scale as the end of the 
thread which is fixed to the plant rises with its growth. 
