Why bother splicing genes?

THE techniques of gene manipulation give biologists deep scientific insight into organic life. But will the practical application of such techniques do more than traditional plant breeders and industrial chemists can achieve? So far, such applications have been modest. But in the long run, genetic engineering may yield more far-reaching results.

For example, gene splicing promises to help plant breeders by speeding up their work. They can bring out new traits in a plant in one or two generations. That means producing new strains in months, compared with years with traditional techniques.

Genetic engineering also allows breeders to combine traits from different species -- or even include animal genes in plants -- which is impossible with traditional breeding. Eventually, animals also may be given new, agriculturally valuable traits.

For industry, many chemicals that have been hard or expensive to synthesize can be made more readily and cheaply by giving bacteria the genetic instructions for making them. Ultimately, genetic engineers even hope to replace defective genes in humans -- that is, to correct genetic defects linked to certain diseases.

In short, the tools of genetic manipulation not only make possible a breakthrough in basic biological knowledge, they promise practical benefits that would be impossible without them.

But because they do manipulate organic life in a fundamental way, their use involves equally fundamental moral, legal, and ethical issues.