Haseman made his long journey with a very slender equipment, his extraordinarily successful field-work being due to his bodily health and vigor and his resourcefulness, self-reliance, and resolution.  His writings are rendered valuable by his accuracy and common sense.  The need of the former of these two attributes will be appreciated by whoever has studied the really scandalous fictions which have been published as genuine by some modern “explorers” and adventurers in South America; and the need of the latter by whoever has studied some of the wild theories propounded in the name of science concerning the history of life on the South American continent.  There is, however, one serious criticism to be made on Haseman:  the extreme obscurity of his style—­an obscurity mixed with occasional bits of scientific pedantry, which makes it difficult to tell whether or not on some points his thought is obscure also.  Modern scientists, like modern historians and, above all, scientific and historical educators, should ever keep in mind that clearness of speech and writing is essential to clearness of thought and that a simple, clear, and, if possible, vivid style is vital to the production of the best work in either science or history.  Darwin and Huxley are classics, and they would not have been if they had not written good English.  The thought is essential, but ability to give it clear expression is only less essential.  Ability to write well, if the writer has nothing to write about, entitles him to mere derision.  But the greatest thought is robbed of an immense proportion of its value if expressed in a mean or obscure manner.  Mr. Haseman has such excellent thought that it is a pity to make it a work of irritating labor to find out just what the thought is.  Surely, if he will take as much pains with his writing as he has with the far more difficult business of exploring and collecting, he will become able to express his thought clearly and forcefully.  At least he can, if he chooses, go over his sentences until he is reasonably sure that they can be parsed.  He can take pains to see that his whole thought is expressed, instead of leaving vacancies which must be filled by the puzzled and groping reader.  His own views and his quotations from the views of others about the static and dynamic theories of distribution are examples of an important principle so imperfectly expressed as to make us doubtful whether it is perfectly apprehended by the writer.  He can avoid the use of those pedantic terms which are really nothing but offensive and, fortunately, ephemeral scientific slang.  There has been, for instance, a recent vogue for the extensive misuse, usually tautological misuse, of the word “complexus”—­an excellent word if used rarely and for definite purposes.  Mr. Haseman drags it in continually when its use is either pointless and redundant or else serves purely to darken wisdom.  He speaks of the “Antillean complex” when he means the Antilles, of the