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Theodore Roosevelt (1858–1919). Through the Brazilian Wilderness. 1914.

Page 363

general conclusions from the results of his own observations and from the recorded studies of other men; and there is nothing more needed at the present moment among our scientific men than the development of a school of men who, while industrious and minute observers and collectors and cautious generalizers, yet do not permit the faculty of wise generalization to be atrophied by excessive devotion to labyrinthine detail.
  Haseman upholds with strong reasoning the theory that since the appearance of all but the lowest forms of life on this globe there have always been three great continental masses, sometimes solid sometimes broken, extending southward from the northern hemisphere, and from time to time connected in the north, but not in the middle regions or the south since the carboniferous epoch. He holds that life has been intermittently distributed southward along these continental masses when there were no breaks in their southward connection, and intermittently exchanged between them when they were connected in the north; and he also upholds the view that from a common ancestral form the same species has been often developed in entirely disconnected localities when in these localities the conditions of environment were the same.
  The opposite view is that there have been frequent connections between the great land masses, alike in the tropics, in the south temperate zone, and in the antarctic region. The upholders of this theory base it almost exclusively on the distribution of living and fossil forms of life; that is, it is based almost exclusively on biological and not geological considerations. Unquestionably, the