78 



EXPERIMENTS WITH PLANTS 



Stems and other parts of plants may be quickly 

 and evenly marked by means of the apparatus shown 

 in Fig. 64. It consists of a small spool (such -as is 

 used for silk twist) with threads at regular intervals; 

 it revolves on a small wire handle. The spool is first 

 notched at regular distances in the following manner: 

 Two knife-blades are fastened together (by clamps or 

 strong spring clothes-pins) with a strip of wood (about 

 one -twenty -fourth of an inch thick) between them. 

 The double knife is then pressed against the two 

 flanges of the spool, so as to make simultaneously 

 two cuts in each. One blade is then inserted in a cut 



and the knife again pressed 

 down so as to make a fresh 

 cut. By proceeding in this 

 way, all the cuts will be the 

 same distance apart. A small 

 piece of glass tubing is secured 

 (by means of sealing-wax) in 

 the center of the spool, and 

 the thread is firmly wound 

 upon it in a manner shown iii 

 the figure. A piece of wire, 

 inserted in the glass tubing 

 and then bent and twisted as shown in the figure, serves 

 as a handle. The thread may be inked by rolling 

 the spool over a pad (made by wrapping any absor- 

 bent cloth around a stick) saturated with India ink. 



64. Contrivance for 

 marking stems in 

 the manner shown 

 in Fig. 63. 



