CERTAIN SEEDS BURY THEMSELVES IN THE GROUND. 153 
doubt, to the irregularity of the rotatory motion of the awn. Тһе following measure- 
ments give the amounts buried in three cases during a single wetting :— 
$: 
З Р.м.—А seed of 16 mm. length, resting with its point on damp sand. 
9 P.M.—14 mm. of seed projecting above soil. 
9 л.м. (still wet).—10 mm.  ,, J 
Amount buried 6 mm. (2 of them in 2 hours). 
11. 
5 Р.М,--12 mm. of seed projecting. 
9 A.M.— 7 mm. b á 
Amount buried 5 mm. 
AH. 
11.0 А.м.—6 mm. of seed projecting. 
3.15 4M.—2 mm. ,, » 
Amount buried 4 тит. 
On removing the bell glass—that is, on substituting a comparatively dry for a damp 
atmosphere—the awn begins at once, 4. е. in less than one second, to twist in the oppo- 
site direction to the hands of a watch; and as the drying proceeds all the above-men- 
tioned movements are reversed. Тһе following are the times in which the first six 
revolutions were made in once instance :— 
| un Completed i in | 'Turn. Completed i in 
| м. 8 | Ж Е | 
Мела 1902204 No. 4 280 | 
| 2 9:40 | 5 6. D | 
| 9 g U | 6 7 30 | 
| т з, 
the movement being slow at first, then becoming quicker, and then slow again. 
The lower knee (/,) becomes perceptible in from 5 to 10 minutes, the e ior knee (ka) 
begins to be perceptible in from 10 to 15 minutes. Тһе whole рсете of drying — 
be said to be thoroughly complete under two hours (in ап ordinary e TAs 
but the movement during the second hour is extremely slow, and practically almost 
unimportant. : с 
When the drying-process is finished an examination of the seed will show that опе of 
three things has occurred :— : 
(i.) The upward traction which results from the return of the awn to its former wid 
condition frequently pulls the seed out of the soil, especially if the sand used in the 
experiment is dry. 5 
(ii) The seed may, however, be able to withstand the upward traction. 
Qiii.) It may actually be found to be buried deeper than it was at the commencement 
_ Of the drying-process. 4 
Y 
