Mr. R. B. Hinds 07i Geographic Botany, 91 



regions it is the same, from the general similarity of controlling 

 circumstances. Sometimes an analogy will be established be- 

 tween two regions not parallel, when external circumstances are 

 peculiar: the temperate (Iroquois) region of North America 

 presents some analogous features to the subtropic portion of 

 Europe ; the tropics also establish an analogy with temperate and 

 subtropic Europe and America, by the latter possessing indige- 

 nous species of Palmce and CinchonacecRy these families being 

 chiefly tropical. Between corresponding regions in the north 

 and south hemispheres the analogy is also great, since under 

 similar circumstances we everywhere find a similar assemblage of 

 plants. 



When tracing affinity, a closer view of vegetable organization 

 is required, since its existence is drawn from genera. Generally 

 it is found to follow analogy in similar regions ; thus we find 

 it strongly developed in parallel regions in the same hemisphere, 

 and in analogous regions in difi*erent hemispheres. The latter 

 offer some highly interesting comparisons, as also do the resem- 

 blances of affinity between regions which are not parallel. Punica 

 granatum, originally indigenous on the northern shore of Africa, 

 though since spread over the warmer portions of the globe, 

 acknowledges a congener from Guiana, P. nana, the former 

 being an inhabitant of the European subtropic region, the latter 

 of the American north tropic. In this instance the value of 

 the relation is increased, since none are found elsewhere and 

 the means of affinity are few, Punica having but two species. 

 Nowhere is affinity so admirably maintained as between different 

 mountain ranges, the resemblances in their diff*erent alpine floras 

 being so extensive and so similar in widely-spread ranges. The 

 genera existing on one of these is frequently repeated by kindred 

 species on others, whilst the whole contents of a zone will bear 

 a close comparison with those of a similar zone elsewhere. Alpine 

 vegetation, always fascinating, is again linked by interesting affi- 

 nities with various regions : if on elevations within the tropics, 

 the zones passed through in ascent will respectively resemble the 

 subtropic, temperate, and arctic regions. Draba has several 

 species in the mountains of Mexico, connecting the flora with 

 the temperate regions of Europe and Asia where the species are 

 abundant. 



In the relation of identity we possess the closest resemblance 

 in the productions : as the word implies, it consists in the co- 

 existence of some of exactly the same forms in different regions, 

 some of the species of one being indigenous to another. Between 

 parallel regions the identity is of course greatest, but the different 

 parallel regions vary in the intensity of this character. From ob- 

 servations on a great number of species, the average of duplicates 



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