In a breakthrough once considered nearly impossible, French scientists claim to have accomplished a cross-species transfer of behavior by transplanting brain tissue.

The major scientific achievement, however, was manifested in almost comical form - domestic chickens with calls resembling those of the Japanese quail.In a study published Thursday in the journal Science, researchers from the National Scientific Research Center and College of France said they implanted into the brains of five chicken fetuses the tissue taken from parts of the Japanese quail brain believed to control its call.

After the chicks hatched, they were given the male hormone testosterone so they would quickly produce sounds typical of adult birds.

"The crowing sounds of the chickens in the first 10 days after hatching do not resemble the familiar `cock-a-doodle-doo' of adult animals but instead consist of a single loud `squeak' about .5-second duration," which is typical of a quail call's introductory notes, wrote Evan Balaban, a developmental biologist and chief author of the study.

"This really is revolutionary," said Peter Marler, a professor of animal behavior at the Rockefeller University Field Research Center in Millbrook, N.Y., who assisted in the behaviorial part of the study. "No one thought it was possible to change behavior in this way."

The researchers said three of the five chicks "gave crowing sounds that approximated a quail temporal (rhythm) pattern," while two made sounds that, although not chicken-like, were indeterminate.

"We believe that this constitutes the first demonstration of cross-species behavioral transfer brought about by neuronal (brain cell) transplantation," the French scientists wrote.

The researchers noted they studied only the rhythm aspect of the bird calls, conceding none of the chicks produced "a structurally perfect quail crow."

Fifteen chicks whose brains had been implanted with different types of quail brain tissue gave crowing sounds similar to those of normal chickens, which researchers said showed neither surgery nor the simple presence of quail cells in the brain affected the call patterns. Also, apart from quail-like feathers on their heads, the quail-chicks looked and acted like normal chickens.