288 



GROWTH 



369. Measurement of Growth by Simple Lever Auxanometer. 

 Secure a rapidly growing specimen of Narcissus, Arisaema, or any 

 convenient plant with a leaf or stem that exhibits but little 

 nutation, and grows rapidly. Set the pot containing the plant 

 directly beneath the loop depending from the short arm of the lever 

 of the auxanometer (Fig. 137). Attach a small spring clamp to 

 a length of oiled silk cord, and allow the clamp to fasten upon the 

 tip of an organ which is emerging from the soil or bud, and about 

 to begin rapid elongation. Fasten the free part of the thread to 



FIG. 137. Cambridge lever auxanometer. The pot containing the growing plant 

 is placed between the feet of the tripod support and a thread run to the loop above. 

 The loop, as well as the fulcrum, are attached to the lever by sleeves which may be 

 moved in either direction. The long arm of the lever, bearing a pen, traces a line 

 on the paper covering the cylinder. The clockwork to the left releases a clutch at 

 regular intervals and allows the suspended weight to turn the cylinder through a small 

 arc of revolution at regular intervals, the length of which is under control of the 

 operator. 



the loop on the short arm of the lever at such length that the 

 long arm of the lever is raised and is in contact with the surface 

 of the cylinder near its upper end. Adjust the lever previously 

 so that the two arms will bear the ratio of one to six. Now 

 remove the cylinder from position and fasten to it a sheet of 

 smooth paper covering its entire surface. Hold in the smoke 



