318 



BOOKS AND CURRENT LITERATURE 



not be better for biological philosophy to let chance and accident go, and 

 deal frankly with its own ignorance or failure to analyze? Such points 

 are at present of little importance, however, considering the prevalent 

 trend of biological thought and the very valuable character of Professor 

 Henderson's main thesis, and the book is to be highly recommended to 

 every one who is interested in natural phenomena. — B. E. Livingston. 



Life Zones of New Mexico.— Field work by Bailey^ and other mem- 

 bers of the Biological Survey, has been embodied in a bulletin on the 

 life zones of New Mexico. The physical relief of New Mexico is re- 

 sponsible for a diversity of flora and fauna which is so great as to bring 

 within its boundaries six of the seven life zones which are recognized 

 by Merriam and his workers as occurring in the United States. The 

 bulletin under notice is most interestingly illustrated, is supplied with 

 copious lists of species, and includes a map of the zones of the state on 

 a scale of 21 miles to the inch. 



Although this publication does much toward giving us a more precise 

 knowledge of the biogeography of a state which exhibits a complex in- 

 terdigitation of regions, nevertheless it does nothing to increase our 

 confidence in the theoretical basis which has been used in distinguishing 

 the regions. Bailey states that "the temperature during the season 

 of growth and reproduction controls the ranges of animals and plants, 

 and therefore determines the extent and limits of the several zones," a 

 statement which can be assailed and refuted from a dozen points of 

 view. In the delimitation of the life zones in New Mexico the distri- 

 bution of yellow pine has been taken as the criterion for the bounds of 

 the Transition Zone, in spite of the fact that the lower limit of this tree 

 in the mountains of the southwest is one of the most striking and well 

 known cases of the limitation of a forest type through edaphic and at- 

 mospheric moisture conditions. The Upper Sonoran Zone is shown to 

 have an upper subdivision characterized by nut-pine and juniper, and 

 a lower characterized by grasses, cacti and yuccas. Here — within one 

 of the life zones — -is a contrast of vegetation as great as that between the 

 Lower and- Upper Sonoran Zones themselves. In describing the Big 

 Hatchet Mountains the statement is made that "the north slope above 

 7000 feet should be Transition Zone in climate, although the mountains 

 are very barren and no characteristic species of the zone were recorded." 

 A description follows of the Upper Sonoran species characteristic of the 



1 Bailey, Vernon, Life zones and crop zones of New Mexico. No. Am. Fauna 

 No. 35, pp. 100, Was hington, 1913. 



