Page:Popular Science Monthly Volume 73.djvu/244

240 of pure scientists, working for the most part in obscurity, most of the insects in each civilized district have been described and named, and much has been made known concerning their habits. This knowledge is about as important a tool to the husbandman as is his plough.

In passing it need only be mentioned that the agitation for the protection of native birds, a movement that the farmers are at last beginning to support, originated not with agriculturists, but with scientific ornithologists. The farmer, left to his own prejudices, would kill all birds.

In another way pure science has aided agriculture, in improving varieties. The chief method in use is selection, planting each new generation from the seeds or cuttings of the best plants of the previous one; the most fit are selected and propagated. This method has been in use for more than a century, but it is only within the past fifty years that it has entered into general systematic employ. The man whose labors brought this method into dominance was Charles Darwin, who proved how important a factor selection is in the perpetuation and guidance of the changes of living beings. Now Darwin was not called a practical man; he was first an insect collector and geologist, then a traveler, lastly a most conscientious experimenter with an eye single to explaining. He discovered a natural factor in evolution, and illustrated it so fully on both wild and cultivated species that the world has accepted its truth. Before him men had applied selection rather unwittingly, on the general assumption that "blood will tell." After him they saw clearly into the workings of the principle, and now experiment with a fixed method. It is Darwin's method that the Department of Agriculture is trying to teach the farmers.

Then much work has been done to secure improvement by the crossbreeding or hybridizing of different varieties. It was Darwin again who was the first broadly scientific investigator of such inheritance. Take two plants or two animals which differ in one or more qualities and cross them, then it is to be expected that the hybrids will differ from the parents, and that a new strain or breed may be obtained that will prove more favorable for our particular purposes. Much of this kind of experimentation, perhaps the greater part, has been done so far by practical animal breeders and gardeners, and it was from such records that Darwin obtained much of his information. No one, for instance, has carried it out more extensively than Burbank, and he has had in mind marketable returns. Yet the theoretical study of hybridizing is coming to aid the other, and in time may come to direct it. Different kinds of inheritance are now distinguished, as blended inheritance, when the hybrid is intermediate between the two parents; mosaic, when it has some of the characters of the one and some of the