32 FERNS IN THEIR HOMES AND OURS. 



"fewer storms than at present," and "a less rapid 

 movement of general circulation," with "an excess 

 of carbonic acid in the atmosphere." Now, this is 

 just the climate which we seek to create in our 

 hot-houses, except that we do not increase the 

 usual percentage of carbonic acid. If we look 

 over the earth for the nearest approach to the cli- 

 mate of the Carboniferous Period which Nature at 

 present exhibits, we discover it on some of the 

 tropical islands ; and here, as might be expected, 

 are the finest ferns, and in the greatest variety. 



Smith gives the following numbers of species 

 for different localities : 



ISLANDS. 



Ceylon 214 species. 



Mauritius 235 " 



Java . . . . . . . 460 " 



Philippines 297 



Fiji 185 " 



British West Indies . . . . 340 " 



MAIN LAND WITH SIMILAR CLIMATE. 



Brazil 387 species. 



Parts of India 319 " 



Isthmus of Panama . . . . 117 " 



Tropical America . . . . 946 " 



Contrast with these 



North America, north of Mexico . 150 species. 



All Europe 67 " 



Asia Minor and Syria . . 25 " 



Arctic Zone . 26 



