20 
the same, or a different flower of the same species, should reach the stigma or top 
part of the pistil. Some flowers are capable of self-fertilization ; but it has been 
proved by experiment that it is more advantageous to the future plants that they 
should be fertilized by polien from other specimens ; and it will be found on ex- 
amination that there are several very beautiful contrivances by which self-fertili- 
vation is prevented. These are either in the structure of the flower or in a 
difference in the time that the pistils and anthers reach maturity. In some 
plants, too, the staminate flowers are all borne on one individual plant, while the 
~pistillate are on another; but it is necessary that the pistils should be fertilized 
by pollen from the anthers, and this is generally effected by insects carrying pollen 
on their bodies from one flower to another when visiting them in search of honey. 
To ensure these visits just at the time when the flowers are in full vigor, this 
nectar is secreted to attract them. Of course, flowers can only be fertilized by 
pollen from flowers of the same species, aud it is a remarkable fact that a bee 
only visits the flowers of one certain species of plant during any one journey, 
and further, that honey only developes in flowers just when the essential organs 
care mature. There isa most remarkable and interesting book just published 
called “ Flowers and their unbidden guests.” It is by Dr. Kerner, Professor of 
Botany in the University of Innsbruck, and translated from the German by W. 
Ogle, M.D. It is, perhaps, the most valuable contribution yet written 
towards demonstrating the principle which, I believe, should actuate every 
student of Natural History, viz.: finding a use for everything that nature has, 
made. The author holds the opinion that the position, direction, and shape of the 
leaf is of just as great significance for the preservaticn of a species as the form, 
colour and smell of a flower ; and that rot even a hair is meaningless whether 
found on the cotyledon, the leaf, the stem, or the blossom. In fact, he proves 
that these contrivances are formed, among other things (for they have probably 
more uses than one) for the prevention of those small flying insects, which are 
too small to touch both the anthers and stigma of a flower, and also those creep- 
ing ones which, from not having wings, are unlikely to go immediately from 
one plant to another, from obtaining the nectar. These contrivances, as I have 
said, are of many kinds. In some plants there is a viscid ring in the middle of 
each joint of the stem, as in our own Silene antirrhina ; in others, as Polygonum 
Pennsylvanicum, the short stalks which support the flowers are embellished with 
viscid glands. This is also the casein Linnea borealis, the lovely little flower known 
‘by the name of Twin Flower. In some the leaves meet in a ring round the 
stem, and thus form a cup which collects dew and rain, and entirely isolates the 
stem, and so prevents creeping insects from mounting. In some plants we find 
thorns, which are most effectual barriers to all soft-bodied animals as snails and 
slugs. As arule, too, the closer to the flower the greater is the accumulation ; 
everyone must have noticed that in the common thistle the lower leaves are much 
less prickly than the upper. The form of the flower, in many instances, acts as a 
barrier to useless insects, In the common garden antirrhinum, or snap-dragon, 
