296 
INFLUENCE OF CLIMATE ON VEGETATION, 
The southern tropical and sub-tropical zones comprehend the New Hebrides, New- 
Caledonia, and the Polynesian group in the Pacific Ocean ; a broad slice of the South 
American continent, including Equador, Guiana, Peru, the principal part of Bolivia, 
part of Paraguay, Brazil ; then Trinidad, Ascension, and St. Helena in the Atlantic ; 
Congo, Benguela, Bechnana, Natal, Mozambique, and Zanzibar in Africa ; the Islands of 
Madagascar, Mauritius, Bourbon, Java, Timor, &c., in the Indian Ocean ; the southern 
point of New Guinea, and the northern half of Australia, the boundary line traversing a 
little to the south of the Tropic of Capricorn, setting in about Shark's Bay, and running 
out nearly opposite Sandy Islands. 
Mean Temp. : 60° — 70°. The northern warmer temperate zone extends along the 
coast of the Pacific to Monterey, in Upper California, taking in Lower California, the 
remaining northern part of Mexico, Texas, the southern States of America, following 
about the 36° of lat. ; then crossing the Atlantic it takes in the Azores and the Canaries ; 
Morocco, Algiers, and Tunis on the African coast ; the greater part of Spain and Portugal 
on the opposite European coast ; Corsica, Sardinia, Sicily, Italy, Asia Minor, Thibet, and 
China, of the latter country, including the coast line from about Fou-tchou to the 35° of 
lat. beyond the mouth of the Yellow River. 
The southern warmer temperate zone does not include much land. On the South 
American continent it takes in the Pacific coast from about the 18° to 30° of lat., and 
stretches across the southern part of Bolivia, part of Chili, southwards to Coquimbo, 
including La Plata and Paraguay, and taking in the southernmost point of Brazil, including 
on the Atlantic coast, from about the 25° to the 38° of lat. In Africa it takes in the 
Cape Colony ; then passing to Australia, it takes in the southern half of that country, in- 
cluding the settlements of West and South Australia and New South Wales ; Norfolk 
Island, and about half the northern Island of New Zealand, from the Bay of Isles to the 
Bay of Plenty. 
Mean Tem]j~ : 50° — 60°. This indicates what we have called the temperate zone. 
The northern zone takes in the northern part of California not before included, and the 
bulk of the United States, including a portion of Lake Michigan, but excluding Oregon on 
the Pacific side, and New York on the Atlantic side. In Europe it includes nearly all 
Ireland, England as far north as York, France, Germany, Austria, Turkey, a point of the 
Russian Empire between the Black and Caspian Seas ; in Asia, Tartary, the northern 
part of China, part of Mongolia and Mandchouria, Corea, and Niphon, the principal island 
of Japan. 
The southern zone comprehends Chili and Chiloe, part of Patagonia southwards to 
the Gulph of St. George; Van Diemen's Land, and nearly all the remaining part of 
New Zealand. 
Mean Temp.\ 40° — 50°, and 32°— 40°, Northwards these zones comprise the north- 
west coast of America, Canada, Labrador, Newfoundland, Scotland, Iceland, Norway, 
Sweden, Lapland, Friesland, Russia, Western Siberia, Mongolia, &c. 
Southwards it includes Patagonia— the remaining part, Terra del Fuego, Falkland 
Isles, Kerguelen's Land ; Auckland's, Campbell's, and some other islands. 
The foregoing divisions refer only to latitude ; but the results are materially altered 
by taking altitude into consideration. A greater or less distance from the equator, is 
coincident with a higher or lower degree of temperature ; and a greater or less degree of 
elevation is also found coincident with a higher or lower temperature. The exact and 
detailed distribution of plants into groups requiring a certain mean annual temperature, 
becomes therefore a compound calculation, which the limits of these remarks cannot 
include. 
It is found, however, that the decrease of temperature from the sea-level, or from the 
plains to the snow-line, is sufficient, constant, and uniform to admit of approximate, if not of 
exact calculation. Presuming on the correctness of Meyer's data as a basis, we shall now 
attempt to divide the altitudinal range into regions, corresponding to the isothermal 
latitudinal zones already sketched out; this division indicates a rise of 3040 feet for 
a decrease of 10° mean temperature, as is more clearly shown in the annexed table : — 
