CLIMATE AND SPECIES. 
1.—CLIMATIC ZONES.—There are various conditions or 
factors, the combination and interaction of which go to the 
production of climate in any region—heat and cold, or the range 
of temperature; humidity and rainfall; the winds, according to 
their prevailing direction; the nature of the surface, whether 
flat, irregular or hilly, rocky or otherwise; the presence or absence 
of trees; latitude, longitude, and altitude. On these the climate 
depends, and, consequently, the kinds of plants which are found 
in a given area, and their distribution. Mr. Watson has repre- 
sented in his Compendium of the ‘Cybele Britannica” the 
combined effect of some of the above conditions in his scheme 
of regions and zones, which may be briefly expounded as 
follows :—By taking the upper limit of grain crops as the median 
line we get a bisectional division for Great Britain; the upper 
designated the Arctic region, the lower the Agrarian. Each 
region is on the same principle divided into three zones, the 
infer- mid- and super-arctic and the infer- mid- and super-agrarian, 
one zone being distinguished from its neighbour by certain 
plants which are characteristic of it, and which disappear in 
ascending to the zone above. As we go northward plants descend 
to a lower altitude, till on the north coast of Scotland alpine 
plants may be found almost at sea-level; in other words, lati- 
tude may be said to have a depressing effect on the zones going 
north, and conversely an elevating effect on those going south. 
The contrast is especially marked in Derbyshire owing to the 
fact that the southern portions of it lie at a low level, and the 
northern reach a decidedly high elevation. No better scheme 
than Mr. Watson’s has been put forth, nor more useful in 
determining the relation of the flora to the physical character 
