202 ROMANCE OF LOW LIFE AMONGST PLANTS. 



fragments of old roots. All we can claim for them 

 is that all these agarics flourish upon their matrix, 

 deriving their nourishment from the substance upon 

 which they grow, which must be nitrogeneous, and 

 consist more or less of vegetable or animal matter 

 diffused through the soil, and not its inorganic 

 constituents. 



Of the residue of the Hymenomycetes little requires 

 to be said. Nearly all the Polyporei, and most of 

 the T/ielephoj-ei, grow on rotten wood, which is pene- 

 trated by the mycelium. Two familiar species — 

 Polyporus Jiybridus and Menilius lacrymans, both 

 known as " dry rot," are in evidence for their power 

 of destruction. 



Pre-eminent above these saprophytes are all those 

 parasites which attack living plants, and compass 

 their destruction. There can be no doubt about the 

 rusts and brands, the whole family of the Uredineae, 

 the rust and mildew of wheat, the hollyhock disease, 

 the plum-leaf rust, all of them determined foes of the 

 plants upon which they flourish. Who shall estimate 

 the losses which they are capable of inflicting upon 

 the cultivator ? and yet there are upwards of twelve 

 hundred different species which attack various plants, 

 and some unfortunate hosts are the victims of two 

 or three distinct species, all of which appear to defy 

 the ingenuity of man to eradicate them. 



Equally injurious in their effects and persistent in 

 their attacks are the " rotting moulds," of which the 

 potato-disease is one form, the American vine-disease 

 another, besides many others which are only of less 

 importance because the plants they attack are less 



