On the Prevention of Mildew. 



83 



powers remained perfect, would have generated an oak- 

 branch, will, when debilitated, give existence to a species of 

 fungus. But, if this power exists, and becomes capable, 

 during its rapid declension, of deviating so widely from its 

 original mode of action, the species of fungus it would pro- 

 duce, might be expected to become successively more feeble 

 and diminutive; whereas the most robust and gigantic of 

 the whole genus, the Boletus squamosus, springs from wood, 

 when that is in its last stage of decay : and the best known, 

 and the most valuable species to mankind, of this tribe of 

 plants, the common mushroom, appears as obviously to 

 spring from horse-dung, under favourable circumstances, as 

 any species of the same tribe appears to spring from decom- 

 posing wood, without the previous presence of seeds.* Yet 

 it can scarcely be contended that any vital powers, capable 

 of arranging the delicate organization of a mushroom, can 

 exist in horse-dung ; and the admission of any such power 

 would surely lead to the most extravagant conclusions. For, 

 if a mass of horse-dung can generate a mushroom, it can 

 scarcely be denied that a mass of animal matter, an old 

 cheese, may generate a mite ; and if the organs of a mite 

 can be thus formed, there could be little difficulty in believ- 

 ing that a larger mass of decomposing animal matter might 

 generate an elephant, or a man. 



The hypothesis, therefore, which supposes the various 

 species of fungus to spring from seeds, appears to me much 

 the least objectionable ; and, if the minute bodies, which 

 are supposed to be the seeds of these plants, be really such, 

 it will not be difficult to shew that these are sufficiently 



* See NicoFs Forcing, Fruit and Kitchen Gardener, 4th Ed. page 119. 



