DISPERSAL OF SEEDS. 148 
forming the pappus. The hairs of this plant have been, and pos- 
sibly are now, used for stuffing pillows, etc. Experiments have also: 
been made with a view to using it as a substitute for Cotton, but not. 
with any great success. The Willows and Poplars also possess this 
arrangement of hairs on the seed, as also do the Valerians and many 
others. 
Many very small seeds that are ripened in capsules of various 
forms, are so light that they can be blown along in a strong wind 
with dust: many of them can, no doubt, travel considerable distances 
in this manner. Wallace in his book ‘‘ Darwinism” gives a table of 
approximate weight and size of some small seeds. 
( 
|Approximate : 
S z ER anbor Approximate 
pecies. Seeds Dimensions Remarks, 
per grain. inch, 
ager eee 
Draba verna 2% 1800 60 X 90 X iso] Oval, flat. 
1 1 By 
Hipericum perforatum afl 520 30 X a | Cylindrical. 
* hirsutum Pe 700 - wv, =) Cylindrical, rough 
Mimulus luteus a ole 2900 = x = Oval, minute, 
Orchis maculata 15000 = Poo tine i 
Yo 8 1 
Sagina procumbens . ..|- 12000 a Sub-triangular 
| z flat. 
As this table shows, these seeds are all very minute, many 
more are as small, and are adapted for wind dispersal; CAMPANULA 
LATIFOLIA, LINARIA VULGARIS, DiciraLis, ANTIRRHINUM, Papaya, 
and many others too numerous to mention. 
One curious case of a seed adapted for this mode of dispersal is 
the Lambs-Lettuce (VALERIANELLA AURICULA) the fruit has three cells 
but only one contains a seed, the other two are larger than the one 
that contains the seed, thus making the whole fruit much lighter 
