276 LAWS OF ANIMAL DISPERSION. 
as we recede toward the poles. Throughout these 
vast spaces however, numberless exceptions and 
deviations from this general ordination occur in 
consequence of the influence of secondary or partial 
laws, as will be shown in the sequel ; but the fact 
of the tropical countries being the great seat of. 
animal creation, the temperate regions possessing 
fewer, and the polar districts the least number, is 
‘incontrovertible. 
But not only do the intertropical regions contain 
the largest proportion of animals both as regards 
species, and as regards the number of individuals, 
but they are characterized also by giving place to 
the most highly organized creatures of the whole 
series ; while the temperate climates, and polar 
regions, are respectively characterized by animals 
having less and less of this endowment. Corres- 
ponding latitudes will therefore be found to agree 
in their animal productions in so far as they will 
ptesent to view creatures possessing similar de- 
grees of organic endowment. ‘These statements 
however, although defensible in a general way, 
are greatly qualified by secondary influences, as 
will subsequently appear. 
The laws which we have here stated, will receive 
elucidation by reference to the Fauna of continental 
mountains, where, on a small but similar scale as 
regards temperature, we see the progressive ad- 
vancement of numbers, and of organization, from 
the summit to the base, though the occurrence of 
highly and of lowly organized beings in both ex- 
tremes forms a partial exception to the principle. 
it would almost appear that we had arrived at the 
knowledge of one of the primary causes of natural 
phenomena, in finding such definite results in con- 
nexion with heat and cold; but there are too many 
and too palpable exceptions to this rule to allow of 
such a conclusion., If animals were governed in 
