Oekologie. — Geographie. 53 



cases there is a gradual replacement of the xerophytic and 

 hydrophytic societies by more and more mesophytic societies 

 until the climax forest condition is reached. 



H. N. Whitford. 



Bray, William L. , The Ecological Relations of the 

 Vegetation of Western Texas. (Contributions from 

 the Huil Botanical Laboratory. XXX. Botanical Gazette. 

 XXXII. 1901. p. 99— 123; 195—217; 262—291. With 24 text 

 figures.) 



The author discusses the climatic and edaphic factors, 

 showing that there are wide variations in temperature from 

 north to south and in altitude, also in moisture from east to 

 west. As a consequence all floristic elements from tropical to 

 „transition" are represented , as well as a wide variety of 

 ecological climatic formations, from semi-mesophytic forests to 

 arid desert-like areas. The physiographic and geologic pro- 

 vinces are found in general to coincide with characteristic plant 

 formations. The aspect of the region as a whole is xerophytic, 

 though of several grades; mesophytic Vegetation is present along 

 streams and on the mountains. 



Originally grass formations were the dominant type, and 

 among these the so-called buffalo grass Vegetation was the 

 most widespread. As a result of artificial conditions, parti- 

 cularly overpasturage and the checking of fires, there is now 

 going on a rapid and extensive encroachment of ligneous 

 Vegetation upon the original grasslands. The xerophytic 

 chaparral thickets in particular are rapidly increasing in area. 

 The natural woody Vegetation is subdivided into arborescent 

 and chaparral formations. In general the timber is best deve- 

 loped on stream or mountain slopes, and there are various 

 formations, largely dominated by oaks or conifers. There are 

 two types of chaparral, one Mexican, the other more western 

 in relationship. Other prominent formations are characterized 

 by the dominance of Cacti, Yuccas, and Agaves. Annual species 

 are prominent in the prairie formations. 



H. C. Cowles. 



The Botany of the Faeröes based upon Danish in- 

 vestigations. Part 1. Copenhagen (and London). 1901. 

 gr. 8^ 340 pp. Mit 1 Karte, 9 Tafeln und 50 Figuren im 

 Text. 



Dieser Band enthält eine historische Einleitung durch 

 Eug. Warming, eine geologisch-geographische Uebersicht 

 durch C. H. Ostenfeld, eine Bearbeitung der Gefässpflanzen 

 durch denselben, der Moose durch C. Jensen, der Süsswasser- 

 algen durch F. Börgesen, der Süsswa.sseT-Diaiomeen durch 

 E. 0strup, der Pilze durch E. Rostrup und der Flechten 

 durch J. S. Deichmann Branth. Ein folgender Band wird 



