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 3i9 " 



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 " 



