20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 



tion that the flora of the Carboniferous grew in a supertropical 

 climate with a humid atmosphere charged with carbon dioxide, of 

 which Koppen and Wegener make such specious use, had as its 

 original basis the i8th century idea that the strange plants associated 

 with the coal had been swept to Europe from the tropics by Noah's 

 flood and the further fact that the habit and venation of certain fern- 

 like Carboniferous plants, now referred with strong probabilitv to 

 the Pteridosperms. resembled certain existing tropical ferns. 



European students accustomed to the modern accumulations of 

 peat in high latitudes concluded quite as illogically that peat could 

 not accumulate in the present equatorial region because of the rapid 

 oxidation there, so added carbon dioxide to make growth extraor- 

 dinarily rapid and great moisture to prevent rapid oxidation. The 

 carbon dioxide stimulation would also conveniently account for the 

 enormous size of some of the calamites and lepidodendrons as com- 

 pared with their diminutive survivors the equisetums and clubmosses. 



Then Koorders and Potonie described a peat bog from Sumatra and 

 others have been subsequently described from other tropical lands, 

 and there has been much readjustment of views, which might have 

 been accomplished much earlier if the experts on geological climates 

 had ever visited the tropics or even consulted the report on the peat 

 deposits of Florida published by the Geological Survey of that state. 



There is not space at my disposal to follow the vagaries of opinion, 

 but it may be stated in the most positive wa}' that teuipcrature or the 

 position of any region with respect tO' the equator,^ that is between 

 hot or cold climate, is not a factor in the formation of either peat or 

 coal. Second the tropical idea relies on representatives of long lived, 

 vigorous groups with very many species, which either in the past or 

 in the present have become adapted to a variety of habitats, as is 

 usually the case in large vigorous groups of all kinds of organisms. 



As outstanding examples I may cite just a few types such as the 

 palms, and figs, or such genera as Cinnamomum and Zizyphus. The 

 great bulk of the existing palms are tropical and they are one of the 

 first types of plants visualized when we think of tropical climates, 

 whether we picture the Arab and his date palms or the South Sea 

 Islander and his cocoanut palms. Nevertheless certain palms extend 

 to approximately 39° South in Chile, 44° South in New Zealand, 

 34° North in California, 35° North in North Carolina and 36° North 

 in Japan, and commonly are hardy several degrees north of their nat- 

 ural limits, as in the Sacramento valley in California, or in southern 



^ Not considering the subtropical arid belts of high pressures. 



