Merchant, James. Alfred Russel Wallace: Letters and Reminiscences. New York: Harper. $5.

This fascinating book gives for the first time in full the historical correspondence between Darwin and Wallace, the codiscoverers of the law of natural selection or of the survival of the fittest, as Herbert Spencer calls it. The reader here finds how these two great and brilliant minds traveled by parallel but independent roads towards this momentous discovery, how Wallace finally came in a flash of inspiration to a conclusion toward which Darwin, for 20 years, had been heaping up the evidence, and how Wallace's thunderbolt drove Darwin to publish his conclusions sooner than he intended. The letters also show how generous and magnanimous the two men were in admitting each other's claims, and reveal the interesting lifelong friendship and mutual esteem that existed between them.

Not the least interesting of the chapters is devoted to Wallace's interest in the phenomenon of spiritualism. In the summer of 1865 he witnesses phenomena called spiritualistic and was surprised to find them real. He says:

"I came to the inquiry utterly unbiased by hopes and fears, because I knew that my belief could not affect the reality, and with ingrained prejudice even against such a word as 'spirit' which I have hardly yet overcome." He did much to establish the facts, as he believed them to be, on a scientific foundation, but met little response from his brother scientists, except from Professor Crookes, who also came to believe in their reality. Huxley wrote him:

"I am neither shocked nor disposed to issue a commission of lunacy against you. I have half a dozen investigations of infinitely greater interest to me. I give it up for the same reason I abstain from chess — it's too amusing to be fair work, and too hard work to amusing."

Wallace was also greatly interested in astronomy and in social progress and reforms. He finally came to call himself a socialist.

He lived well beyond 90, active and interested to the last. In fact, some of his finest and best work was done in these last years in such books as "The World of Life," "Social Environment and Moral Progress" and "The Revolt of Democracy." The book gives a fine picture of his home life and of his mind and his ways of working.