450 GEORGE PERKINS MARSH. 



detail to each author for what he has found useful in his works would 

 have encumbered the book with an intolerable bulk of references. 

 The author has wisely avoided doing so whenever the matter did not 

 seem to require, by its novelty or strangeness, the suppoi-t of some 

 recognized authority. In these cases the statement is generally given 

 in the woi-ds and with the name of the writer who is responsible for it. 



The book has three principal divisions. First, an introductory 

 chapter exhibits the character, extent, and vai-iety of man's action 

 on Nature. Next, four chapters treat in detail of man's influence 

 upon animal and vegetable life, the forest, the waters, and the sands. 

 Finally, a most suggestive and useful chapter deals with the great 

 projects which this century has brought forth for the modification of the 

 physical character of our globe. 



Under the first of these heads we are shown how some of the most 

 flourishing provinces of the Roman Empire have been brought to a 

 condition of hopeless decay by neglect of those terms which Nature 

 imposes upon those to whom she permits such wonderful control over 

 her own operations. Man, who could not exist in a civilized state 

 without in a measure unbalancing Nature's stable equilibrium, has per- 

 sistently exceeded that measure. His action has, on the whole, been 

 destructive, although in some places and in recent times there is a 

 reverse to this melancholy picture. There are regions first peopled by 

 Europeans not more than two hundred years ago which already show 

 signs of dilapidation. 



The author then enters upon a detailed description of man's inter- 

 ference with Nature in respect to animal and vegetable life, showing 

 how he promotes the growth of certain species of plants and animals 

 often changing their nature in a wonderful degree by his care and cul- 

 tivation, — how he greatly reduces the numbers of other animals and 

 plants, often altogether expelling certain animals from particular re- 

 gions, and sometimes, though rarely, effecting, or at any rate greatly 

 hastening, the annihilation of certain species. Mr. Marsh illustrates 

 the matter by copious examples culled from his prodigious and ency- 

 clopedic reading. It would be hopeless to attempt to give any ad- 

 equate idea of their variety and interest. Few men indeed are so 

 minutely acquainted with historical botany and zoology, and with the 

 practical side of natural history, as not to find in these pages a rich 

 harvest of the most interesting and instructive details. 



No less remarkable is the author's chapter on forests, their position 

 in the economv of Nature, their influence on climate, on torrents and 

 inundations, on health, and the importance of man's operations involv- 

 ing their destruction or conservation. 



