FUNGI. 187 



easily to be carried about by every current of air. Persons 

 in health may inhale and swallow these spores, and escape 

 injury from them. Other persons, depressed physically 

 from local or accidental causes, may afford to them just the 

 pabulum which will develope their poisonous quality. 



Many animal organisms, such as infusorial animalcules 

 and their ova, are frequently found floating about in the 

 air, as well as the fungi spoken of. 



The upholders of the spontaneous hypothesis were con- 

 siderably shaken by an experiment instituted by Schultze, 

 and recorded in the Edinburgh New Philosophical Journal 

 for 1837. He found that if the decomposing substances, 

 which always generate infusoria and fungi when the atmo- 

 spheric air is freely admitted to them, be shut up in vessels 

 to which the air is admitted only after passing through a 

 red-hot tube, or through strong sulphuric acid, no animal- 

 cules or fungi appear. The experiment seemed conclusive. 

 By destroying these germs which the sulphuric acid 

 did without altering the air all development was pre- 

 vented. 



All the fungi that constitute mouldiness are so small as 

 to escape observation ; they clothe the surface of the body 

 which they attack with light patches of yellow, blue, 

 green, red, and various other colours ; they are all inter- 

 esting objects for microscopic observation. The species of 

 these plants are extremely numerous ; they chiefly belong to 

 the Hyphomycetous division of the order; the peculiar cha- 

 racteristic of which is, that the plants are flocculent, naked 

 (that is, not enclosed in a case, or seated upon a peculiar 

 receptacle), distinct, but interwoven into a general mass, 

 which looks like a thin web, or a collection of cobwebs. 



One of the most common is the Ascophora mucedo, 

 which forms a blue mould upon bread, paste, and sub- 

 stances prepared from flour : this is even found to live 

 under circumstances that would be fatal to any other 

 form of vegetation ; that is, it flourishes in paste mixed up 

 with a solution of the well-known poison, bichloride of 

 mercury. 



Their favourite soil is decaying animal or vegetable 

 matter; but one species, the Botrytis bassiana, attacks the 

 living silkworm just as it is about to enter the chrysalis 



