Jeff Pratt, age 16, of Hattiesburg, Miss., for his question:

WHAT IS WALLACE'S LINE?

Wallace's Line is an imaginary line in the southwestern Pacific that divides the animal life of the Australian region from that of the Asiatic, or oriental, region.

The Wallace Line starts at the Philippines and extends west, separating Celebes from Borneo and Bali from Lamock. Scientists named the line for Alfred Russel Wallace, an English naturalist.

Wallace's researches convinced him that no two species are identical if they develop under different geographical and climatic conditions, even though they may be descended from a common ancestor.

The animals of the southwest Pacific are supposedly different on the two sides of the line.

Wallace was an explorer in addition to being a naturalist. He became famous by reaching independently the same explanation for evolution as Charles Darwin did. He also laid the basis for the study of animal geography.

Wallace spent five years in the Amazon Valley and nine in the East Indies collecting data on animals. He lived from 1823 until 1913 and wrote a number of important books.