In hermaphrodite plants (the normal case), and even as the question is ingeniously put by De Candolle in the above extract, the former surely cannot be the cause of the latter, though it may, in case of crossing, offer occasion. But, on the ground of the most fundamental of all things in the constitution of plants and animals--the fact incapable of further analysis, that individuals reproduce their like, that characteristics are inheritable--the likeness is a direct natural consequence of the genetic succession; "and it is logical to place the cause above the effect." We are equally disposed to combat a proposition of De Candolle's about genera, elaborately argued in the "Geographie Botanique," and incidentally reaffirmed in his present article, viz., that genera are more natural than species, and more correctly distinguished by people in general, as is shown by vernacular names. But we have no space left in which to present some evidence to the contrary. V SEQUOIA AND ITS HISTORY THE RELATIONS OF NORTH AMERICAN TO NORTHEAST ASIAN AND TO TERTIARY VEGETATION (A Presidential Address to the American Association for the Advancement of Science, at Dubuque, August, 1872) The session being now happily inaugurated, your presiding officer of the last year has only one duty to perform before he surrenders the chair to his successor. If allowed to borrow a simile from the language of my own profession, I might liken the President of this Association to a biennial plant. He flourishes for the year in which he comes into existence, and performs his appropriate functions as presiding officer. When the second year comes round, he is expected to blossom out in an address and disappear. Each president, as he retires, is naturally expected to contribute something from his own investigations or his own line of study, usually to discuss some particular scientific topic. Now, although I have cultivated the field of North American botany, with some assiduity, for more than forty years, have reviewed our vegetable hosts, and assigned to no small number of them their names and their place in the ranks, yet, so far as our own wide country is concerned, I have been to a great extent a closet botanist. Until this summer I had not seen the Mississippi, nor set foot upon a prairie. To gratify a natural interest, and to gain some title for addressing a body of practical naturalists and explorers, I have made a pilgrimage across the continent. I have sought and viewed in their native haunts many a plant and flower which for me had long bloomed unseen, or only in the hortus siccus. I have been able to see for myself what species and what forms constitute the main features of the vegetation of each successive region, and record--as the vegetation unerringly does--the permanent characteristics of its climate.