Most people would agree that it would be wonderful if humans could regenerate (再生) limbs. Those who have lost their arms or legs would be complete again. The day is still far off when this might happen. But in the last 10 years, doctors have reported regeneration in smaller parts of the body, most often fingers.
Regeneration is not a newly-discovered process. For centuries, scientists have seen it work in some kinds of animals. Scientists now are looking for a way to turn on this exciting ability in more highly-developed animals, including humans. Their experiments show that nerves (神经), cell chemistry and the natural electric currents in the body all seem to have a part in this process.
The body of every animal contains general purpose cells that change into whatever kind of cells the body needs. These cells collect around the wound. They form a mass called a blastema (芽基). The cells of the blastema begin to change. Some became bone cells, some muscle cells, some skin cells. Slowly, a new part re-grows from the body outward. When completed, the new part is just like the old one.
More than 200 years ago, Italian scientist Luigi Spallanzani showed that younger animals have a greater ability to regenerate lost parts than older animals. So do animals lower on the ladder of evolutionary (进化的) development. The major differences seem to be that less-developed animals have more nerves in their tails and legs than humans do in their arms and legs.
Another helpful piece of information was discovered in the late 1800s. Scientists found that when a creature is injured, an electrical current flows around the wound. The strength of the current depends on how severe the wound is and on how much nerve tissue (组织) is present.
59．According to the passage, limb regeneration ________.
A. will become a reality in the near future
B. has been reported successful in some patients
C. has a long way to go before it works in humans
D. is a branch of study set up by a group of modern doctors
60．What animals are lower on the ladder of evolutionary development ?
A. More-developed animals. B. Less-developed animals.
C. Highly developed animals. D. Fully-developed animals.
61．According to Luigi Spallanzani’s discovery, ________.
A. humans have less nerves in the limbs than animals
B. some animals may not have so much nerve tissue as others
C. an injured animal regenerates masses of cells round the wound
D. electrical current can be found around the would in younger animals
62．The passage is mainly about ________.
A. a newly-discovered process B. research on animal evolution
C. a new medical discovery D. research on regeneration
