588 



METASPERMAE OF THE MINNESOTA VALLEY. 



come in their final analyses, like other problems of biology, 

 studies in evolution. The understanding of relationships is 

 prior to the understanding of juxtapositions, separations or 

 isolations of species, individuals, families or formations. The 

 knowledge of embryology, phylogeny, comparative anatomy, 

 classification, help to a knowledge of relationship. By the study 

 of buried plants, fossil in the rocks of former ages, by the inti- 

 mate observation of developmental stages in the plants of to- 

 day, by the systematic examination and enlightened arrange- 

 ment of all forms of plants and animals living within the range 

 of human observation, and by the critical comparison of 

 results in each of these three departments of scientific botany, 

 lies the method of reconstructing the past history of vegeta- 

 tion. Such a reconstruction must perforce be general in its 

 character, tentative in its statement of details. Nevertheless 

 there are some conclusions that present themselves and these 

 will be discussed in their proper place. 



NATURAL VEGETATION REGIONS OF THE EARTH. 



Grisel)ach : Under the notions of separate centers of devel- 

 opment the most important classification of the land areas of 

 the globe into vegetation- regions is that of Grisebach. By 

 this writer twenty four regions are recognised, as follows: 



I. Arctic region. XIII. 



II. Forest region of the Eastern XIV. 



Continent. XV. 



III. Mediterranean region. XVI. 



IV. Region of the Asiatic XVII. 



Steppes. 

 V. Chinese-Japanese region. XVIII. 



VI. Indian-Malayan region. 

 VII. Sahara region. XIX. 



VIII. Soudan, or Central African XX. 



region. XXI. 



IX. Kalahari region. XXII. 



X. Cape of Good Hope region. XXIII. 

 XI. Australian region. XXIV. 



XII. Forest region of the West- 

 ern Continent. 

 Eiigler : Under the notions of general development and mi- 

 gration the most important classification is that of Engler. By 

 this writer the surface of the globe is divided into four princi- 

 pal realms ( Florenreichen), each of these into regions and each 

 region into provinces. The realms and regions are as follows: 

 A. Northern Extra-Tropical Realm. 



(1) Arctic region. 



(2) Sub-Arctic, or Conifer region. 



Prairie region. 



Californian Coast region. 



Mexican region. 



West Indies region. 



Cisequatorial South Am- 

 erican region. 



Hylaea, or Amazonian re- 

 gion. 



Jirazilian region. 



Tropical Andes region. 



Pampas region. 



Chilean transition region. 



Antarctic forest region. 



Oceanic Island region. 



