28 LEHKBUCH DEE OKOLOGISCHE PFLANZENGEOGEAPHIE. 



Lehrbuch der vkologische Pjianzemjeographie. Eine Einfuhrumj in 

 die Kenntnis der Pjianzenvereine. Von Dr. Eugen Warming. 

 Deutsche Ausgabe von Dr. Emil Knoblauch. Berlin : Born- 

 trager. 1896. Pp. xii, 412. Price 7 Mark. 



The German translation of Warming's Plantescaiifund. Grund- 

 triik af den okologiske Phintegeof/rqfi will be welcomed in this 

 country by not a few botanists who are unable to read the original. 

 It is a valuable work, for it indicates the direction in which we 

 must look for future development in botany. The laboratory 

 worker and the naturalist converge. The key to our plant-lists and 

 floras, and the general facts of geographical distribution, lies partly 

 in the internal and external structure of the plants themselves, 

 and the careful observation of the relations of anatomy and 

 morphology to surrounding conditions will help us to find it. 

 We should like to see an English translation, for it is a book 

 which should be read by all botanists and naturalists. It would 

 open up long vistas of useful work for men who are now wasting 

 their thne in the multiplication of brambles or in equally futile 

 occupations. 



Oecological plant-geography, as defined by the author, teaches 

 us how plants and plant-societies adapt their form and their 

 domestic economy to the factors acting upon them ; for instance, 

 to the amounts of warmth, light, food, water, &c., at their disposal. 

 The most casual glance shows that in any given plant-area species 

 are not equally divided, but are grouped in societies with widely 

 differing physiognomies, each of which offers a three-fold problem. 

 We must first determine what species occur together in similar 

 stations, next the general appearance of the vegetation, and finally 

 we have to attack the question, "Why are the species thus associ- 

 ated, and why has the vegetation its peculiar physiognomy ? " As 

 species are the units of the systematist, so for the oecological plant- 

 geographer are the " Lebensformen," which nearly correspond with 

 Humboldt's plant-forms and Grisebach's vegetation-forms. Rarely 

 do we find the same "Lcbensform" common to the species of a 

 family, as in the Nymph(Bacem, where in harmony with the same 

 conditions the same habit has been assumed. On the other hand, 

 the same life-form may characterise families which are widely 

 separated from a systematic point of view. A familiar example is 

 the cactus type, which occurs also in the cactus-like euphorbias 

 and stapelias. It is of importance to define a limited number of 

 easily recognizable life-forms, and here again we meet a difficulty. 

 What biological points are of the greatest importance and to form 

 the basis for our oecological system ? "It cannot be enough 

 emphasized that the greatest advance, not only for biology in the 

 broader sense, but also for oecological geography, will be the 

 definition of the different life-forms : a goal from which we are still 

 far distant." 



The last task is the investigation of the plant-societies (" Plante- 

 samfund") occurring in nature. These generally contain many 

 species with widely differing forms. Such are meadows with their 



