Science: Ova Transfer

Always ready to tinker with the basic life processes if they can improve the breed, agricultural geneticists have experimentally transplanted embryos of cows, sheep and mice from high-quality mothers to lower-quality "incubator" females of the same species. Their goal: to allow champion breeders to conceive more offspring in less time, pass on the lengthy trials of pregnancy to their lesser sisters.

Last week, carrying embryo-switching one drastic step farther, three British geneticists reported in Nature that they had successfully transferred female eggs from one species to another.

The three scientists — R. L. W....