188 Mr. W. Murton Holmes on the 
A striking instance of the temporary storage of pollen occurs 
in the arrow-grass, a plant growing in marshes and on the mar- 
gins of ponds. The development of the stigmas precedes that of 
the stamens by two or three days. During the period that the 
stigma remains in a receptive condition the anthers remain 
closed, and only open when the stigma has faded. Underneath 
each stamen is a deeply concave perianth-leaf. When the anther 
opens the pollen falls into this receptacle, and in the meantime 
the perianth-leaf becomes less closely adherent to the axis, so 
that when a puff of wind comes the pollen is shaken out and 
dispersed. 
Another remarkable case of wind-fertilization occurs in the 
Vallisneria spiralis, a plant growing under still water and often 
cultivated in aquaria. The female flowers are borne on a long 
spiral stalk, which is pushed above the surface of the water 
when the stigma is ripe. The male flowers are produced abun- 
dantly, and, becoming detached from the plant, rise to the 
surface. At first they are closed and globular, but soon open, 
showing a pair of stamens covered with sticky pollen, projecting 
obliquely, the sepals forming little boats, which are blown here 
and there by the wind, until it happens that one of the anthers 
comes into contact with the stigma of the female flower, and 
there deposits the pollen. Directly after the adhesion of the 
pollen the female flower closes and is withdrawn to the bottom 
by the contraction of the spiral stalk, and there ripens the seed. 
The grasses, among which are included wheat, barley, oats, 
and reeds, are also fertilized by the agency of the wind. Here 
the anthers swing freely from the flowers at the extremities of 
their filaments. The anthers open by means of a slit near the 
bottom, the dry pollen falling into the little cup formed by the 
recurved portion of the anther-lobe, and as this is blown away 
by gusts of wind, more pollen takes its place until the whole is 
discharged, when the anther shrivels and drops off. 
In the foregoing cases the wind is said to be the agency 
whereby fertilization is brought about, but as many insects are 
great consumers of pollen, it is possible that fertilization may 
also sometimes be due to them, as they pass from flower to 
flower, and shake the pollen from the stamens. In all cases of 
wind-fertilization there is evidently very great waste of pollen, 
much more being produced than can by any possibility be 
utilized, the chances being so much against the pollen-grains 
being deposited on the right spot; but as insects became more 
and more accustomed to visit flowers, the latter also adapted 
themselves to this circumstance, becoming more brightly 
coloured, giving off a fragrant odour, and moreover secreting 
honey, so as to give a fitting welcome to their insect guests. 
A further development would be necessary for the shelter of 
