NA TURE 



79 



THURSDAY, MARCH 27, 1913. 



FOREST PHYSIOGRAPHY. 

 Physiography of the United States and Principles 

 of Soils in Relation to Forestry. By Prof. I. 

 Bowman. Pp. xxii + 759. (New York: J. 

 Wiley and Sons; London: Chapman and Hall, 

 Ltd., 1911.) Price 215. net. 



AS the longer title of this work denotes, this is 

 not a book on forestry, but on physiography 

 for students of forestry, and especially for those 

 of the United States. The book is in two parts, 

 the first of which forms a complete treatise on 

 the subject of soils, and it is this part which will 

 be of most interest to foresters and nature- 

 students in this country. The second and larger 

 part is devoted to a description of the United 

 States, according to physiographic regions, in 

 regard to geology, climate, soil, and vegetation. 



In reading this book one cannot fail to be im- 

 pressed by the prominence given to the question 

 of water and water-supply. "Water constitutes 

 from 65 per cent, to more than 95 per cent, of the 

 tissues of plants," and "is the factor that most 

 frequently conditions life and death." Water is 

 also the natural force which is most capable of 

 being controlled by man : by the preservation of 

 soil-cover and by a proper system of drainage 

 promoting its beneficial influences and checking its 

 dangers. In this connection Fernow is quoted as 

 saying : 



"The leaf canopy catches and re-evaporates 

 about 12 per cent, of the rainfall, while 10 per 

 cent, of it runs along the tree-trunks and reaches 

 the ground by a circuitous course. The forest 

 litter, the moss-covered and leaf-strewn ground, 

 is capable of absorbing water at the rate of 

 40,000,000 to 50,000,000 cubic feet per square mile 

 in ten minutes — water whose progress is delayed 

 by some twelve to fifteen hours after the first 

 effects of a heavy freshet have passed." 



The author deplores the reckless timber-cutting 

 which has taken place in America during the last 

 twenty-five years, with the result that the soil, 

 "the inheritance of geologic ages," has in many 

 cases been washed away or impoverished. In a 

 striking paragraph, in dealing with the evil effects 

 of deforestation in the southern Appalachians, he 

 writes : 



"The rain beats directly upon the soil, the re- 

 tarding influence of the ground litter and tree- 

 roots is withdrawn, and more rapid soil removal 

 occurs. When once these evil effects have been 

 allowed to take place, mankind is deprived prac- 

 tically for thousands and even millions of years of 

 the favourable conditions that preceded the epoch 

 of destruction. In a hundred years man may 

 achieve such baneful results as nature will com- 

 NO. 2265, VOL. 91I 



pensate only during a geologic period of hundred ; 

 of thousands of years. Soil is a resource of price- 

 less value. On resistant rocks its formation is 

 excessively slow. Many glacial stria? formed on 

 resistant rock during the last glacial epoch, 

 roughly 60,000 to 75,000 years ago, are still pre- 

 served as fresh as if they were made but yester- 

 day. In that time man has come up from the 

 cave and the stone-hammer. Seventy thousand 

 years is a very short time for the development of 

 a soil-cover ; for man it means a period so great 

 that his mind can hardly appreciate it. The earth 

 as we find it in the geologic to-day must be trenkd 

 with care if the human race is to have a fair dis- 

 tribution of its wealth in time. To the geologic- 

 mind there is something shocking in the thought 

 that a single lumber merchant may in fifty years 

 deprive the human race of soil that required 

 10,000 years to form." 



Although forests undoubtedly tend to regulate 

 stream-flow, the author is careful to show that 

 they are not an absolute preventive of flooding, 

 and that in individual cases their influence may be 

 quite insignificant. It is largely a matter of soil 

 and situation, but where soil removal exceeds soil 

 formation, or where the balance between the two 

 is only delicately established, the destruction of 

 forests can only be attended by disastrous con- 

 sequences. 



The chemistry of the soil, the effects of sun, air, 

 wind, the beneficial influences of the lower fo. nn 

 of vegetable and animal life, are each dealt with 

 in a concise though comprehensive manner, and 

 frequent footnotes give authorities for statements 

 made and references to further literature on the 

 various points discussed. 



A key-list giving the scientific names of the 

 trees referred to by their common names would be 

 of value, and there are a few minor errors which 

 should be corrected in future editions. 



The book is admirably produced, and fully illus- 

 trated by diagrams, maps, and photographs, and 

 forms a most useful addition to the literature of 

 the subject. J. W. Mackay. 



THE HIGHWAY OF ANIMAL EVOLUTION. 



The Evolution of the Vertebrates and their Kin. 

 By Dr. William Patten. Pp. xxi + 486; illus- 

 trated. (London : J. and A. Churchill, 1912.) 

 Price 215. net. 



THE author presents in a stately form a 

 detailed account of his theory of the 

 Arachnid origin of vertebrates. He has worked 

 at this persistently since 1S84, and in the course 

 of his investigations has made important contribu- 

 tions to our knowledge of Limulus and the 

 Ostracoderms. No one will withhold admiration 

 who looks into the details of comparative 

 anatomy, histology, and embryology with which 



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