290 Floristik, Geographie, Systematik etc. 



werden einzeln genannt). Die Grenzen der pontisch-illyrischen Flora 

 werden von der Art nie überschritten. Die Mykorhiza dieser Pflanze 

 zeigt alle bei Neottia vorgefundenen Eigentümlichkeiten, nament- 

 lich aber schön die Zellstoffklumpen in den Pilzverdauungszellen. 



Matouschek (Wien). 



Crampton, C. B., The Geological Relations ofStable and 

 Migratory Plant Formations. (Scott. Bot. Review I. n" 1—3, 

 reprint 61 pp. 1912.) 



An amplification of a view already expressed (Bot. Cent. 1 19. 

 p. 111). The author regards as a point of first importance in defi- 

 ning the habitat of a plant formation, its condition relative to geo- 

 logical agents of surface change; in other words the habitat is 

 determined less by climate or some edaphic condition, than by 

 topography. Two classes of habitats are distinguished, differing in 

 plant succession, and two classes of plant formations are defined 

 which differ in their centres of distribution. "Stahle formations are 

 those whose plant associaiions have their centres of distribution on 

 ground which has been for a long period comparatively stable from. 

 the geological Standpoint, and under climatic conditions favourable 

 to the type of Vegetation". "Migratory formations are those whose 

 plant associations have their centres of distribution in areas within 

 the sphere of influence of the geological agents of surface change". 

 The stable formations are relatively unchangeable since they are 

 stabilised so far as the prevailing climate and edaphic conditions 

 allow. Migratory formations are comparatively short-lived on the 

 same habitat since this changes or is destroyed within short periods. 



The regional succession of stable formations (p. 8—13) is partly 

 due to migralion and competition of plants and animals, but the 

 author considers that it chiefly originates in extensive geological 

 transformations or secular changes in climate and geography. These 

 changes include those resulting from mountain-building, displace- 

 ment of the coastline, glaciation. volcanic action, and agents of 

 erosion, all of which are discussed. 



The relation of soils to climate and physiography (p. 14 — 28) is 

 treated from the Standpoint that soil-characters depend more on 

 geography and climate than on the local nature of the underljnng 

 rocks. Considerable attention is given to the influence of limestone 

 on Vegetation and it is shown that this varies widely in dry and 

 humid climates, and with the elevation and exposure of the rocks 

 above the base level of erosion; thus there is the contrast between 

 the scanty Vegetation of high exposed masses of dry limestone as 

 compared .with the rieh Vegetation of calcareous lowland soils. A 

 grouping of calciphile plants from the point of view of their phy- 

 siographic relation is given: aquatics, lithophytes, reed-swamp, 

 mesoph3'tes, etc. 



The stable t5'^pes of Vegetation in Br itain (p. 28 — 39) are moor- 

 land, woodland, heathland and grassland. For each of these and 

 for plant associations included within them it is shown that the 

 primary factors of distribution are mainly topographical; thus the 

 woodland occurs in places protected from excessive wind and with 

 the higher summer temperature, while the distribution of the trees 

 is partly a result of resistance to unfavourable conditions, partly 

 an outcome of competition. 



The migratory formations fp. 40 — 59) centre mainly round: 



