TEE A WAKENING OF THE SEED 



49 



seed is about half submerged, it will soon begin to 

 swell and force the free arm to move, thus stretching 

 the spring and causing the indicator of the balance 

 to move also. If a small piece of glass be smeared 

 with vaseline and placed in front of the indicator, 

 it will move forward with it and record the highest 

 pressure reached. We may now set the balance at 

 any desired pressure by lengthening or shortening one 



38. Arrangement for testing the swelling power of a single seed. 



of the wire loops, or by turning the nut, or by both 

 methods, and leave it for forty- eight hours. If at 

 the end of that time an increase of pressure has been 

 registered, we may replace the seed by a similar one 

 of about the same size, taking care to set the balance 

 at the outset at a somewhat smaller pressure than the 

 highest recorded in the experiment just finished. 



The experiment should be watched and the pressure 

 recorded from time to time. It must be remembered 



