Distribution of Fungi. 277 
already taken place in the more thickly peopled districts, as, for 
example, in the vicinity of New York 
There is this difference between the Fungi and other vegetable 
productions—that the former scem to be especially dependent on 
the existence of humidity, whilst heat is the more essential con- 
dition to the development of plants of a higher organization. 
Thus it is that the richness of vegetation in general and its whole 
aspect differ so remarkably, according as the country in question 
varies in regard to temperature, whereas the amount of atmo- 
spheric moisture and rain predominates as the cause which most 
materially determines the differences in the vegetation of Fungi. 
Meteoric forms are likewise met with among the higher Fungi, 
which become developed principally in hot years, and in locali- 
ties which are, as a rule, under water, but have become dried up 
by the heat. A parallel to this is to be found among those 
Phanerogamia which in nature make the nearest approach to 
Fungi, as, for example, Orobanche and Monotropa, which flourish 
in the greatest abundance when the temperature ranges high 
and repeated rains sodden the soil. 
Further, the circumstance that the higher forms of Fungi 
more especially flourish during the colder weather at the close 
of autumn, such as, for instance, Agaricus velutipes, A. serotinus, 
A, melleus, &e., proves that heat is not an indispensable condi- 
tion to the growth of these plants. Still it cannot be denied 
that the fungaceous vegetation is usually more luxuriant if there 
is an abundant fall of rain in August; and it is under such cir- 
cumstances that the Amanite and Bolett make their appearance 
in the greatest number. From the fact of North America, 
where rain falls very copiously, being one of the countries most 
fruitful in Fungi that is known, the deduction may be fairly 
drawn, that moisture is a physical condition peculiarly favourable 
to the development of those plants. 
The globe is divisible into several zones, according to the de- 
gree of heat, and its more or less unequal distribution through- 
out the course of the year: but, so far as the geographical dis- 
tribution of the Fungi is concerned, these divisions have very 
little practical or useful application ; for the differences discover- 
able between the fungaceous vegetation of particular regions are 
not so strongly marked as in other cases, and it often happens 
that countries widely separated possess the closest affinities in 
reference to their indigenous Fungi. It is enough to admit of 
the existence of two zones, peculiar in their fungaceous growths— 
namely, a temperate and a tropical zone; for the frigid zone of 
geographers produces no peculiar types different from those of 
the temperate zone; it is merely poorer in species. As to the 
tropical and subtropical zones, no essential distinction can he 
Ann, & Mag. N. Hist. Ser. 3. Vol. ix. 20 
