1917] CURRE.XT LITERATURE . 333 



for mapping. On the whole, 18 types of plant communities are recognized, 

 briefly characterized, and plotted. An inspection shows, as its author points 

 out, that the areas have in general a north and south rather than an east and 

 west trend, which tends to show that the major differences in vegetation are 

 here determined more largely by conditions of moisture than of temperature. 

 While the result is decidedly the best map of the sort yet produced, it is 

 also probable that it would be difficult to find an ecologist who would agree 

 with it in every particular. So much of the disagreement would be differences 

 of opinion as to what should be included within a single vegetational type, that 

 diverse criticism would be neither a gracious nor a practical task, and yet the 

 reviewer cannot refrain from expressing a question as to the fitness of including 

 both the Pinus ponder osa and P. Murray ana forests of the west and the P. 

 Strobus, Tsuga, and Abies balsamea forests of the east in the " northern meso- 

 phytic evergreen forest."— Geo. D. Fuller. 



History of forest ecology,— A recent study of the historical development 

 of forest ecology is likely to prove of equal interest to foresters and ecologist s. 

 In it Boerker 26 traces the development of plant ecology from its beginnings 

 to the modern phase characterized chiefly by efforts to measure the various 



habitat factors. 



ecology 



development of silviculture, dating back to the fifteenth century or even earlier; 

 but the founder of the science is considered to be Duhamel du Moxceau, 



niddle of the eighteenth century. About a century later the work 



Hartig 



Wessely, Heyer, Ebermayer, Judeich 



science further impetus, and resulted in the organization of a series of forest 

 experiment stations throughout Germany. From this beginning the advance- 

 ment of the science is traced to the present day, as shown in the work of 

 Wagner, Meyer, and Duesberg in Germany, and that of Fernow and Zox 

 m America. It is notable that not until 1909 were forest experiment stations 

 established in the United States.— Geo. D. Fuller. 



Permeability 



modify 



(light, 

 1. In 



some cases the stimulus decreases the permeability at low intensity and increases 

 it at high intensity. Koketsu 27 believes he has demonstrated that electrical 

 stimulation increases the permeability of epithelial cells of Tradescantia dis- 

 color. Cells thus stimulated are less easily plasmolyzed by ordinary plas- 

 molytic agents than are unstimulated cells. After recovery from the stimulus 

 they show a greater degree to plasmolysis by the same concentration of the 



Boerker, R. H., A historical study of forest ecology; its development in the 

 fields of botany and foresty. Forestry Quarterly 14:380-432- J 9 l6 - 



27 Koketsu, R., Uber den Einfluss der elektrischen Reizung auf die Permea- 

 bilitat der Pflanzenzellern. Bot. Mag. Tokyo 30:264-266. 1916. 



