RACES. 363 



problematical influence of climate on races. " Families of 

 animals and plants," writes one of the greatest anatomists of 

 the day, Johannes Miiller, in his noble and comprehensive 

 work. Physiologic dcs Mcnsclten, " undergo, within certain 

 Limitations peculiar to the different races and species, various 

 modifications in their distribution over the surface of the 

 earth, propagating these variations as organic types of spe- 

 cies.* The present races of animals have been pr duced by 



* [In illustration ol'this, the conclusions of Professor Edward Forbes, 

 respecting the origin and diffusion of the British flora, may be cited. 

 See the Survey Memoir already quoted, On the Connection between the 

 Distribution of the existing Fauna and Flora of the British Islands, 

 &o., p. 65. " 1. The flora and fauna, terrestrial and marine, of the 

 British islands and seas, have originated, so far as that area is concerned, 

 since the meiocene epoch. 2. The assemblages of animals and plants 

 composing that fauna and flora, did not appear in the area they now 

 inhabit simultaneously, but at several distinct points in time. 3. Both 

 the fauna and flora of the British islands and seas are composed partly 

 of species which, either permanently or for a time, appeared in that 

 area before the glacial epoch ; partly of such as inhabited it during that 

 epoch ; and in great part of those which did not appear there until 

 afterward.;, and whose appearance on the Earth was coeval with the 

 elevation of the bed of the glacial sea, and the consequent climatal 

 changes. 4. The greater part of the terrestrial animals and flowering 

 plants now inhabiting the British islands, are members of specific 

 centres beyond their area, and have migrated to it over continuous land 

 before, during, or after the glacial epoch. 5. The climatal conditions of 

 the area under discussion, and north, east, and west of it, were severer 

 luring the glacial epoch, when a great part of the space now occupied 

 by the British isles was under water, than they are now or were before; 

 but there is good reason to believe, that so far from those conditions 

 having continued severe, or having gradually diminished in severity 

 southwards of Britain, the cold region of the glacial epoch came 

 directly into contact with a region of more southern and thermal 

 character than that in which the most southern beds of glacial drift are 

 now to be met with. 6. This state of things did not materially differ 

 from that now existing, under corresponding latitudes, in the North 

 American, Atlantic, and Arctic seas, and on their bounding shores. 

 7. The Alpine floras of Europe and Asia, so far as they are identical 

 with the floia of the Arctic and sub- Arctic zones of the Old World, are 

 fragments of a flora which was diffused from the north, either by means 

 of transport not now in action on the temperate coasts of Europe, or 

 over continuous land which no longer exists. The deep sea fauna is in 

 like manner a fragment of the general glacial fauna. 8. The floras of 

 the islands of the Atlantic reg ; on, between the Gulf-weed Bank and the 

 Old World, are fragments of the great Mediterranean flora, anciently 

 iiffuaed over a land constituted out of the upheaved and never again 



