lid particles, and let us
compare with these the weights of some seeds. From a small collection of
the seeds of thirty species of herbaceous plants sent me from Kew, those
in the above table were selected, and small portions of eight of them
carefully weighed in a chemical balance.[175] By counting these portions
I was able to estimate the number of seeds weighing one grain. The three
very minute species, whose numbers are marked with an asterisk (*), were
estimated by the comparison of their sizes with those of the smaller
weighed seeds.

No| Species. |Approximate | Approximate | Remarks.
| |No. of Seeds| Dimensions. |
| |In one Grain| |
| | | in. in. in. |
1|Draba verna | 1,800 |1/60 x 1/90 x 1/160|Oval, flat.
2|Hypericum perforatum | 520 | 1/30 x 1/80 |Cylindrical.
3|Astilbe rivularis | 4,500 | 1/50 x 1/100 |Elongate, flat, tailed,
| | | | wavy.
4|Saxifraga coriophylla| 750 | 1/40 x 1/75 |Surface rough, adhere
| | | | to the dry capsules.
5|Oenothera rosea | 640 | 1/40 x 1/80 |Ovate.
6|Hypericum hirsutum | 700 | 1/30 x 1/100 |Cylindrical, rough.
7|Mimulus luteus | 2,900 | 1/60 x 1/100 |Oval, minute.
8|Penthorum sedoides | 8,000* | 1/70 x 1/150 |Flattened, very minute.
9|Sagina procumbens | 12,000* | 1/120 |Sub-triangular, flat.
10|Orchis maculata | 15,000* | --- |Margined, flat,
| | | | very minute.
11|Gentiana purpurea | 35 | 1/25 |Wavy, rough, with this
| | | | coriaceous margins.
12|Silene alpina | --- | 1/30 |Flat, with fringed
| | | | margins.
13|Adenophora communis | --- | 1/20 x 1/40 |Very thin, wavy, light.
|Quartz grains | 25,000 | 1/250 |Deep sea ... 700 miles.
|Do. |200,000 | 1/500 |Genoa ... 600 miles.

If now we compare the seeds with the quartz grains, we find that
several are from twice to three times the weight of the grains found by
Mr