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 

 W2 



