Here it is: a facsimile of the original, best-selling 1859 edition of "On the Origin of Species"-- the book that Darwin sweated over for decades and that changed our view of the world. Even to the modern mind it is an outstanding introduction to the subject. It's one of the great works of science -- and surprisingly readable. Darwin tinkered with later editions, mostly in response to his critics, but you may as well read the original. With an introduction by Ernst Mayr.  (NAT19, $19.50)