GETTING ESTABLISBliU 



75 



An arrangement for weighting an 

 upward -growing stem. 



tionary engines does not usually exceed eighty pounds 

 per square inch. 



If a spring is not at hand we may use in place of 

 it a bottle filled with shot, as shown in Fig. 60. 



A simple method of test- 

 ing the force of the upward 

 growth of the stem is by pre- 

 paring a strainer, as shown 

 in Fig. 61, by thrusting the 

 finger upward thi'ough the 

 bottom. The plant is allowed 

 to grow up into the cone thus 

 formed and receives both air 

 and light; shot may be poured into the strainer until 

 the plant can no longer lift the weight. As it is some- 

 what difficult to bal- 

 ance the load, we 

 may use for this pur- 

 pose the apparatus 

 shown in Fig. 62. 

 Three stout wire 

 nails, about five 

 inches long, are 

 driven through holes 

 previously bored in 

 a board so as to be 

 as nearly vertical as 



.i 1 rni 62. Modification of the arrangement shown 



possible. They are inFig.ei. 



