SPOTTING OF LEAVES. 
257 
that itself arises from decay, is found to constitute a 
soil for another; and the termination of this chain of 
efficiency is hidden from us. 
But the leaves of many vegetables often become singu- 
larly spotted during some parts of the summer, and such 
spots have not certainly been effected by the growth of 
cryptogamous plants, natural decay, or the punctures of 
insects, the usual agents in these cases. A very in- 
different observer of these things, in strolling round his 
garden, must have remarked how uniformly and singu- 
larly the foliage of some of the varieties of the straw- 
berry are spotted, and corroded as it were into little 
holes ; whereas other kinds have seldom any of these 
marks visible on them. I have fancied that these spot- 
tings were occasioned by the influence of solar heat ; 
a shower of rain falls, small drops collect and remain 
upon the leaf of the plant ; the sun then darts out, con- 
verting all these globules of rain into so many little 
lenses, converging the rays, and scorching or burning 
a hole at the focus. This conjecture has been rather 
strengthened by observing, that upon certain sorts, the 
„ hautboy, alpine, &c., the rain when it falls uniformly 
wets the leaves, yet they do not become spotted ; but 
the smooth leaves of others, roseberry, Caledonian, upon 
which it stands in drops, always become marked and 
perforated : but whatever may be the real cause of these 
spottings, if the foliage be touched, by way of an ex- 
periment, with the point of a heated wire, after a few 
days they will present an appearance very similar to 
what is naturally effected. 
There seems to be a curious analogy in their func- 
tions between the roots of plants and the moving parent 
of animated beings, a similar obligation being required 
from them both of providing for those dependent on 
them, and both will exert their energies in fulfilment 
of this ordained mandate : the roots of plants wander 
up and down in every direction, seeking for sustenance; 
and we frequently see trees, growing on rocks, extend- 
ing their roots like sensitive beings, searching for mois- 
ture ; if this is not obtained sufficiently, a sickly foliage 
W 2 
