of growth, as the
well-known instance of the _Reticularia_ which Schweinitz observed
running over iron a few hours after it had been red hot. Mr. Berkeley
has observed that the creamy mycelium of _Lycogala_ will not revive
after it has become dry for a few hours, though so active before.

[A] M. J. Berkeley, "Introduction to Cryptogamic Botany," p. 265.

[B] Tulasne, "Sur la Phosphorescence des Champignons," in "Ann. des
Sci. Nat." (1848), vol. ix, p. 338.

[C] In "Hooker's Journal of Botany" (1840), vol. ii. p. 426.

[D] Berkeley, "Introduction to Crypt. Bot." t. 265.

[E] Dr. Collingwood, in "Journal of Linnaean Society (Botany)," vol.
x. p. 469.

[F] In "Hooker's Journal of Botany" for April, 1842.

[G] Tulasne, "Sur la Phosphorescence," in "Ann. des Sci. Nat."
(1848), vol ix. p. 340, &c.

[H] Rev. M. J. Berkeley, in "Gardener's Chronicle" for 1872, p.
1258.

[I] Berkeley, "Introduction to Crypt. Bot." p. 266.

VI.

THE SPORE AND ITS DISSEMINATION.

A work of this character would hardly be deemed complete without some
reference to the above subject, which has moreover a relation to some
of the questions discussed, and particularly of spore diffusion in the
atmosphere. The largest spore is microscopic, and the smallest known
scarcely visible under a magnifying power of 360 diameters. Taking
into account the large number of species of fungi, probably scarcely
less numerous than all the flowering plants, and the immense number of
spores which some of the individuals produce, they must be exceedingly
plentiful and widely diffused, though from their minuteness not easy
to be discerned. It has been attempted to estimate the number of
spores which might be produced by one single plant of _Lycoperdon_,
but the number so far exceeds that which the mind is accustomed to
contemplate that it seems scarcely possible to realize their
profusion. Recent microscopic examinations of the common atmosphere[A]
show the large quantity of spores that are continually suspended. In
these investigations it was found that spores and similar cells were
of constant occurrence, and were generally present in considerable
numbers. That the majority of the cells were living, and ready to
undergo development on meeting with suitable conditions, was very
manifest, as in those cases in which preparations were retained under
observation for any length of time, germination rap