CHAP. X. GEOTROriSM. 515 



grows in dry soil, Imt whether the power of absorption by the 

 hairs on the buried flower-heads is of any importance to them 

 we do not know. Only a few of the flower-heads, which from 

 their position are not able to reach the ground and bury them- 

 selves, yield seeds ; whereas the buried ones never failed, as far 

 as we observed, to produce as many seeds as there had been 

 perfect flowers. 

 We will now consider the movements of the peduncle whilst 



Fig. 190. 



Trifolium sulterrancum : downwar;'. movement of peduncle from 19 beneath 

 the horizon to a nearly vertically dependent position, traced from 

 1 I A.M. July 22nd to the morning of 25th. Glass filament fixed 

 transversely across peduncle, at base of flower-head. 



curving down to the ground. "\Ve have seen in Chap. IV., 

 Fi^r. 92, p. 225. that an upright young flower-head circumnu- 

 tated conspicuously; and that this movement continued after 

 the peduncle had begun to bend downwards. The same 

 peduncle was observed when inclined at an angle of 19 abc e 

 the horizon, and it circumnutated duriug two days. Another 



