Il6 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Conversely, we may add, upland xerophytes are sometimes found 

 in bogs. These facts are probably to be explained in the self- 

 adaptability of plants to new conditions of life ; so that they alter their 

 internal anatomical tissues in adaptations without much external 

 morphological alteration. Such is the case with Ranuncuhis aquatilis 

 when growing in the air. 



As the hills are xerophytic, the hollows hydrophjrtic, and the 

 plains mesophytic, erosion tends to reduce the first and fill up the 

 second; so the process tends to produce a general mesophytic state. 

 The author deals with three aspects of the Inland Group : the 

 River series the Pond-swamp-prairie series ; the Upland series. The 

 Coastal Group contains the Lake-bluff series and the Beach-dune- 

 sandhill series. We may take the first as an example of the author's 

 method of procedure. He commences with The Ravine. Admirable 

 photographs show how, beginning with a ravine, or narrow, more 

 or less deep, channel, cut in a clay moraine, a broad valley is 

 gradually formed, where lateral erosion is more pronounced. From 

 this stage the destructive and constructive processes are considered 

 in the final development of a " flood plain." In the first or ravine 

 stage there is no vegetation, in consequence of the instability of the 

 soil and landslides. Torrents deepen the ravine, which becomies wider 

 with gently sloping sides, when vegetation begins. In a few years, 

 from herbs, it becomes a mesophytic forest, as of maples. 



Having reached a temporary climax of a rich mesophytic associa- 

 tion of forest trees and undergrowth, the erosive processes of the river, 

 widening processes, prevail over the more primitive deepening. As a 

 result the exposure to wind, sunlight &c. increases, moisture becomes 

 less, and a new xerophytic flora shows signs of invasion at the top of 

 the ravine slope. This gradually creeps down the slopes and vegeta- 

 tion becomes much less luxuriant. 



River-bluffs and flood-plains are similarly described from their 

 origin to completion, and how they become inhabited by vegetations of 

 hydrophytes &c. according to the nature of the soil. The above will 

 indicate the author's treatment ; it is interesting as being rather a new 

 departure in the treatment of ecology. 



" Date-growing in the Old and New Worlds." By Paul B. Popenoe. 

 8vo., xviii -f- 316 pp., with 40 full-page illustrations. (West India 

 Gardens, Altadenia, California, 1913.) $2.00 net. 



This book, on a subject about which little has been written in 

 English, is the result of two years' travel and inquiry in the date-growing 

 regions of the East on behalf of the W^est India Gardens, Altadenia. 

 The countries from which the dates of commerce are chiefly derived 

 are Arabia, Mesopotamia, and North Africa, but there are parts of the 

 United States, especially in California and Arizona, where the date-palm 

 has been proved successful, and where in the near future a large and 

 profitable industry in date-growing will probably be established. 



The total annual consumption of dates in the United States is 



