In one department of industry we shall be largely free from this danger, that is, in the extension of agriculture. One of America’s ablest ethnologists, Dr. Charles Pickering, as the result of a lifetime devoted to his science, finally settled upon the extension of cultivated plants as the safest guide in the labyrinth of pre-historic migrations. Its value is easily seen in America when we reflect that the two tropical plants, maize and tobacco, extended their area in most remote times from their limited local habitat about the Isthmus of Tehuantepec to the north as far as the St. Lawrence river and to the south quite to the Archipelago of Chiloe. Their presence is easily traced by the stone or earthen-ware implements required for their use. How many ages it must have required for these plants to have thus extended their domain, amid hostile and savage tribes, through five thousand miles of space! The squash, the bean, the potato and the mandioca, are native food-plants offering in a less degree similar material for tracing ancient commerce and migration. Humboldt and others have claimed as much for the banana (_Musa paradisiaca_), but the recent researches of Dr. Karl von den Steinen have removed that valued fruit from the list of native American plants. Both species of banana (_M. paradisiaca_ and _M. sapientium_) were undoubtedly introduced into the New World after the discovery.[20] Indeed, summing up the reply to an inquiry which has often been addressed to the industrial evolution of the indigenes of our continent, I should say that they did not borrow a single art or invention nor a single cultivated plant from any part of the Old World previous to the arrival of Columbus. What they had was their own, developed from their own soil, the outgrowth of their own lives and needs. _Linguistic._ This individuality of the race is still more strongly expressed in their languages. You are all aware that it is upon linguistic data almost exclusively that American ethnology has been and must be based. The study of the native tongues becomes therefore of transcendent importance in the pre-historic chronology of the Continent. But to obtain its best results, this study must be conducted in a much more thorough manner than has hitherto been the custom.