PRODUCED BY MAN. 



809 



which copper and tin are still found in such proximity to each 

 other and in such accessible abundance as to suggest that it is not 

 improbable that in some one of those districts prehistoric man may- 

 have come upon the invention of bronze. A fourth colour marks 

 the position of the Kuenlun Jade mines i, whence, in still earlier 

 than bronze times, stone weapons may with great probability be 

 supposed to have been procured by man before he migrated into the 

 jadeless regions westward. (See Article XXXIX, p. 686.) 



The New World was coloured as it is in Schouw's tav. viii, 1. c, 

 to show the area of distribution of the Cactaceae, a region com- 

 prehending South America north of the Tropic of Capricorn, the 

 Isthmus of Panama, the Peninsula of California up to 30° N. lat, 

 the West Indian Archipelago, the northern shores of the Gulf of 

 Mexico, and the strip of Gulfstream-washed North American coast 

 between the AUeghanies and the Atlantic up to about 40° N. lat. 

 From this area more than 25 per cent, of all our cultivated plants 

 have been procured, as the annexed table shows ; and, of course, 

 since the time of Columbus. 



This table (based, so far as it deals with the vegetable kingdom, 

 mainly upon De Candolle's ' Geographic Botanique,' pp. 986-987) 

 gives approximatively the proportions in which the several 'regions' 

 of the globe established by that phytogeographer and by several 

 zoogeographers have contributed to make up the lists of such culti- 

 vated plants and domesticated animals respectively as are of con- 

 siderable, even if not always of cosmopolitan, importance. 



Of {approximatively) 160 Cultivated 

 Plants. 



The Palaearctic species are 

 Oriental „ 



African „ 



Nearctic , , 



Neotropical „ 

 Australian ,, 



Per cent. 



25 

 25 



2-5 



25 



o 



Of (approximatively) 2 1 Domestic 

 Mammals. 

 Per cent. 



50 are Palaearctic. 

 14 „ Oriental. 

 14 „ African, 

 o „ Nearctic. 

 14 ,, Neotropical. 

 o „ Australian. 



Of some of the great facts which these maps and this table put 



shore of the Caspian. This tree is supposed to have been carried thither, as to so 

 many other places, by the Arabs during their career of conquest, which contrasts to 

 such advantage and in so many ways with that of other Mussulman conquerors. ^ 

 ^ For an account of the Jade mines in the Kuenlun Range see Cayley. 'Macmillan 8 

 Magazine,' October, 1871 ; and for Jade generally, Rudler « Popular Science Review, 

 October, 1879. 



