Cross-fertilisation of Cereals. 
685 
food stored up in its tissues or beside it within the seed, it forms 
its roots and leaves by which it is able to provide food for 
itself. 
The action of the substance of the pollen grain upon the 
substance of the ovule is the beginning of the life of the new 
plant. The new plant is necessarily affected by both elements. 
When the pollen which fertilises and the ovule which is fer- 
tilised are both parts of the same flower, there is obviously little 
likelihood of modification in the new plant. On the other hand, 
when the pollen comes from the flower of another plant which 
though of the same species has its individual peculiarities, 
modifications will appear in the progeny of the same kind, though 
not so obvious to us as those we are familiar with in the animal 
kingdom, when two different-looking individuals of the same 
species inter-breed. 
In the strict sense this is cross-fertilisation. Greater energy 
comes from it, which is manifested in the production of an 
increased number of larger seeds. The great attention that was 
given to this subject by Darwin, and the results of his numerous 
experiments, have produced an extensive literature dealing with 
the extraordinary and almost endless modifications in the struc- 
ture of many flowers for the purpose of securing cross-fertilisa- 
tion. In many plants, belonging to various sections of the 
vegetable kingdom, cross-fertilisation is necessary because the 
pollen is produced on different plants from those that bear the 
ovules. The most familiar instance of this is found in willows, 
where the seed-bearing catkins are found on shrubs or trees that 
never bear the male or anther flowers. Such plants are called 
dioecious. Very few grasses have flowers of this kind, and none 
of our British grasses or cereals are among that number. 
Another case of necessary cross-fertilisation is found in 
plants where the two kinds of organs are produced in separate 
flowers though both kinds of flowers are borne on the same 
plant. This is familiar in the oak, in which the long slender 
tassels are composed of pollen-producing flowers, while the 
pistil-bearing flowers are less numerous and are borne closer 
to the branch. These plants are called monoecious. Among 
grasses we are best acquainted with such flowers, in maize or 
Indian corn. The male or antheriferous flowers are produced 
on a branched inflorescence which terminates the stem, while 
the female or pistillate flowers are borne in dense spikes (cobs) 
lower down the stem. It would seem 'that the position of the 
staminal flowers would secure when the anthers burst an 
abundant shower of pollen grains on the stigmas of the flowers 
below. But the antheriferous flowers which crown the maize 
