Legs to Order

Another Harvard man, Dr. Marcus Singer, professor of neuroanatomy at the Harvard Medical School, approached the growth problem from another angle: the nerves of amphibians. Newts and salamanders can grow new legs and tails with the greatest of ease. Tadpoles can do the trick too. But when they grow up to be frogs, their more complex bodies can no longer regenerate new members.

About six years ago, Dr. Singer was making experiments on the nervous systems of newts. His chief interest was the nerves themselves, but in the course of the experiments he found out that if he damaged the nerves in the stump of an amputee newt, the newt failed to grow a new limb. Dr. Singer concluded that a hitherto neglected function of the nerves, the promotion and control of growth, was responsible. He decided to experiment further.

Last week in Cleveland he reported startling results. On the theory that insufficient nerve power prevented the adult frog from growing new legs, Dr. Singer had cut the big sciatic nerves out of the hind legs of 21 amputee frogs, folded them back under the skin, and connected them to the stumps of the frogs' amputated front legs. In 20 of the frogs a new foreleg began to grow within three weeks. They were not very good legs. Nevertheless, they were legs.

"One can become wild with speculation as to the significance of this discovery," said Dr. Singer, "but no speculation is yet justified. This work may remain in the realm of abstract reason for many years [but] it does emphasize a function of the nerves that was not as well known as it should be."

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