214 Fruits and Seeds, 



seeds to some little distance. The seeds them- 

 selves are more or less spindle-shaped, hairy, and 

 produced into a twisted hairy awn, as shown in fig. 

 84. The number of spiral turns in the awn depends 

 upon the amount of moisture ; and the seed may 



Fig. 84. Seed of CRANE'S BILL. 



thus be made into a very delicate hygrometer, for 

 if it be fixed in an upright position, the awn twists 

 or untwists according to the degree of moisture, 

 and its extremity thus may be so arranged as to 

 move up and down like a needle on a register. It 

 is also affected by heat. Now, if the awn were 



