170 BOOKS AND CURRENT LITERATURE 



of rain-forest plants based on actual experiment. For the purpose 

 of this valuable research a number of plants were selected, including 

 two of the commonest trees, a common shrub, a thick-leaved herb, 

 two herbs of the forest floor and two extremely hygrophilous ferns. 

 Without going into details here, the author found that the rates of 

 relative transpiration of the rain-forest plants dealt with and those of 

 certain xerophytes of the Arizona desert are of the same order of 

 magnitude, i.e. the rates of transpiration in the two regions are pro- 

 portional to the rates of evaporation that prevail in them. While 

 the plants of the rain-forest are capable of losing much more water 

 per unit area than are those of the desert when the two kinds of plants 

 are exposed to identical conditions, yet as each set exists in its habitat, 

 the desert plant loses far more water per unit area than does the forest 

 plant. This, though in line with certain recent publications, is contrary 

 to the accepted opinion which is based not on experiment but on a con- 

 sideration of the reduced transpiring surface of desert plants. 



One is apt to look upon rain-forest as a purely hygrophilous formation 

 in which xerophytes have no place. This the author rightly shows to 

 be a false conception. "There is no type of vegetation," he declares, 

 "in which may be found a wider diversity of life forms than exist side 

 by side in a tropical montane rain-forest. Together with the structural 

 diversities discoverable in the field or at the microscope, are diversities 

 of physiological behavior, discoverable by observation or experiment, 

 and sometimes correlated with the structural features. There are 

 quite as high degrees of specialization to be found in the rain-forest 

 as may be sought in the desert." 



Much more could be extracted with profit from Shreve's admirable 

 book, the chief fault of which lies in its brevity. One would have 

 welcomed, for instance, a special account of the growth forms ac- 

 companied by statistics for comparative purposes. Ecological works, 

 with few exceptions, seem to take it for granted that the reader is 

 acquainted with the species cited, whereas he frequently knows but 

 little regarding them, and even if assisted by afloramay get far astray — 

 L. Cockayne, Wellington, New Zealand. 



Plant Breeding. — In 1895, Bailey incorporated some excerpts 

 from the writings of Verlot, Carriere and Focke with three of his own 

 lectures relating to the improvement of plants and published the 

 material under the title Plant Breeding. The author's reputation as 

 the leading American agricultural botanist together with his charming 



