48 DEVELOPMENT OF MOULD, MILDEW, &C. 



liable to be attacked by the common bead-mould: which no care 

 employed in completely closing the mouths of the jars can 

 prevent. It has been remarked, however, that they 

 are much less liable to suffer in this way, if not 

 left open for a night before they are tied down ; 

 and it is therefore probable, that the germs of the 

 mould sow themselves, as it were, in this luxuriant 

 soil, before the jar is covered. Again, there is a 

 particular kind of cheese, much valued by some epi- 

 cures, which derives its peculiar flavour from the 

 quantity of fungous vegetation it contains. It is 

 prepared simply by breaking up the curd, and ex- 

 magnified: its posing it for a day or two, in small lumps laid 



stems consist- , , , . . , 



ing of single upon a cloth, to the sun and air ; it there seems 

 Jointed 10 toge^ to rece i ye tne g erm s of Fungi, which afterwards 

 ther. vegetate in it, and spread their growth through the 



mass whilst it is yet soft. 



52. In all these instances, the Fungi derive their nutriment 

 from organic matter, which is either already in a state of decay, 

 or will readily decompose. There can be little doubt, that their 

 development hastens decay when it is slow, or even causes 

 decomposition in substances which previously exhibited none. 

 Thus, a fruit-preserve, into which no mould finds its way, may 

 remain sweet for many years ; but the growth of the mould 

 produces chemical changes in it, which are of a kind to supply 

 the plant with the materials it requires. There is another very 

 remarkable group of Fungi, which develops itself in the midst 

 of the tissues of living plants and animals. To it belong, amongst 

 others, the mildew, rust, smut, &c. of corn and other vegetables ; 

 these are distinct plants, having all the characters of true Fungi, 

 but growing from the ears, stems, &c. of those they infest, so as 

 to appear like a part of themselves. In fact the question has 

 been raised, whether they are really produced from separate 

 germs, or whether they are not diseased parts of the structure on 

 which they appear. But there seems little doubt, that distinct 

 germs are introduced from without. They can be communicated 

 from one plant to another ; and they may perhaps enter through 

 the stomata or breathing - pores hereafter to be described 



