XII. TYPES OF DISTRIBUTION. 517 



manner, respectivelj'^ in their own opposite directions ; a 

 repetition of what is seen in Middle Europe, carried fur- 

 ther south and north. And to these again the plants of 

 the mountains are to be added, first as one primary group, 

 and then as sub-divisible into arctic and alpine and other 

 subordinate groups, according to the geographic sites of 

 the various mountain ranges. 



These differences of distribution are familiar enough to 

 botanists. They are practically recognized in stating the 

 habitats of individual species, though seldom clearly or 

 methodically described. When attempts have been made 

 to divide a whole flora so as to show those differences of 

 distribution, or to apportion the plants into correspond- 

 ing groups, recourse has been had to fixed lines and 

 definite spaces on maps, either actually represented or 

 mentally feigned. The result has proved a sort of com- 

 bination, or rather confusion, of local floras with climatal 

 zones imperfectly brought out, — not the formation of 

 eclectic groups, such as the t3'pes of distribution are 

 intended to be. 



This latter is confessedly an inconvenient designation, 

 waiting the invention of a better name. That of ' flora * 

 would be misapplied to them, as before mentioned ; for 

 these groups are not so many different floras, but so 

 many ingi'edients in one flora. Geographically, a flora 

 may be said to include, or to consist of, various different 

 t3'pes of distribution ; — much as it may be said, systema- 

 tically, to include or consist of various different orders. 

 Though the distributive types cannot be made so nume- 

 rous as the orders, without frustrating the object sought 

 in forming them. 



Possibly, no two species in the whole flora of the earth 

 have a distribution precisely the same. Probabl}^ the 

 species of every country will admit of being classed into 



