CROSS-FERTILISATION OF CEREALS. 
The improved varieties of our cereals now under general cultiva- 
tion have been obtained almost entirely from the selection of 
individual plants which were observed to differ from the rest of 
the crop by their size, or by possessing some other desirable 
quality. A sufficient quantity of seed for practical use has been 
obtained by sowing and resowing the seeds of the selected plant 
and its progeny ; and the purity of the variety has been secured 
by carefully removing all the plants in each generation that did 
not exhibit the characteristics for the possession of which the 
original plant was selected. The intelligence of the grower was 
exercised, not in the production of the variety, but in detecting 
the presence of the original plant in the field, and in producing 
by cultivation a true and fixed form. 
The production of new varieties by crossing or hybridising 
is of comparatively recent origin. It is true that Knight, who 
did great service to agriculture as well as horticulture, tried 
crossing wheats a hundred years ago, and that at intervals 
thereafter similar experiments have been made ; but no practical 
results were secured till recent years. Successful results in 
crossing have been obtained in Germany, France, and America, 
as well as in England. 
To appreciate the process of fertilisation, and the difficulties 
of cross-bi-eeding, it will be well to consider for a little the 
general subject, using for illustration the flower of wheat 
engraved from Bauer’s beautiful drawings (page 687). 
In all plants that have seeds there are produced, in the same 
or in different flowers, two necessary organs — stamens and 
pistils. The function of each of these organs is to prepare certain 
minute bodies — pollen grains in the one and ovules in the other. 
When fully grown these small bodies are incapable of further 
development by themselves. It is not till the materials of two of 
these products of the flower are brought together that further 
development takes place. This is accomplished by the pollen 
grain, when it has fallen on the stigma, sending out a 
minute tube that penetrates the stigma and pushes its way 
through the tissues until it reaches the ovule. As soon as the 
growing apex of the pollen tube touches the ovule, fertilisation 
takes place. A new growth immediately begins in the ovule, 
which ends in the formation of a minute embryo plant. This 
embryo is present in all seeds capable of germination. Under 
suitable conditions the embryo germinates, and, living on the 
