CERTAIN SEEDS BURY THEMSELVES IN THE GROUND. 167 
DESCRIPTION OF PLATE XXIII. 
. Fruit and awn of Stipa pennata (natural size). p, the sharp point; v, the vertical twisted part 
of the амп; Ё, and k, the lower and upper knees; f, the non-twisted and more or less hori- 
zontal part of the awn. 
Fruit and awn of Heteropogon melanocarpus. Letters corresponding to fig. 1. 
. Awn of Androscepia arundinacea. Letters as above. 
. Fruit and awn of Avena elatior. x 6. 
. Carpel and beak of Pelargonium. Letters as above. x 31. 
. Achene and tail of Anemone montana. Letters as above: natural size. 
. Lower part of the fruit of Stipa pennata. х 6$. 
. Achene of Anemone montana. х 5 (about). 
Upper part of v in fig. 1. х 7 (about). r and r аге spirally running ribs, seen in section at 
r and r in figs. 11, 12, 13. 
10. Cotton-wool cells. а, in dilute, 6, in stronger sulphuric acid (from Nägeli). х 200. 
11. Section of awn of Stipa pennata close to seed. т and т hollow spiral ribs (see fig. 9); с, central 
| vascular bundle; m and m smaller masses of the same tissue; с, т, and m are non-hygroscopic. 
| х 80. 
12. Section of awn of Stipa pennata at k,, fig. 1. Letters as in fig. 11. х 80. 
13. Section of awn of Stipa pennata at k, fig. 1. Letters as in figs. 11 and 12. гу, line dividing 
awn into a more and a less hygroscopic part. On the other dotted line see text, p. 160. x 80. 
14. External cells from the awn of Stipa pennata, isolated with nitric acid and chlorate of potash and 
then dried, to show the power of independent torsion residing in the cells of the awn. x about 
100. 
A 
os 
= 
t0 ON ф OW O 0 
SECOND SERIES.—BOTANY, VOL. I. 2A 
