DAILV PERIODICITY OF GROWTH IN LENGTH, 



827 



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, 



I. The Thread-indicator is a simple contrivance in which the free end of the thread 



Fig. 48r.— Autographic Auxanometer, for recording the growth in length during short periods of an internode of a 

 growing plant/"; s s' tlie lines scored by the index z 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. 



