THE PAGE OF NATURE. 227 



mous or entophytic fungi spring from beneath the cuticle 

 of living plants, and a considerable proportion of our 

 flowering plants are affected with them a different 

 fungus being developed upon almost every species. 

 Their minute sporules are either directly applied to the 

 plants upon which they are found, entering by the sto- 

 mata or breathing pores ; or they are taken up from the 

 soil by their seeds in the process of germinating, enter 

 into their structure, circulate through their tissues, re- 

 maining all the time in a dormant state, until at last, 

 when the part which forms the most suitable nidus for 

 them is developed, they suddenly appear upon it exter- 

 nally in the form of patches or aggregations of black or 

 coloured granules. Many species, contrary to the habits 

 of the race, seem to live on mineral matter. Numerous 

 exotic Polypori, for instance, grow on hard volcanic 

 tufa, without a particle of organic matter. Other fungi 

 are not unfrequently found in this country growing in 

 abundance on the hardest gravel stones, and bare plas- 

 tered walls destitute of all organic nourishment. Mr. 

 Ivor found a Didymium on a leaden cistern at Kew ; 

 another was found by Mr. Sowerby, in the outer gallery 

 of St. Paul's, on cinders ; while a still more extraordi- 

 nary instance is related by Schweinitz of a species of 

 JEthalium vegetating on iron which had been subjected 

 to a red heat a short time before. " A blacksmith," he 

 says, " at Salem, by no means void of sense or cultiva- 

 tion, had thrown on one side a piece of iron which he 

 had just taken from the fire, being called off to some 

 other business. On his return in the morning, he was 

 astonished to see on this very piece, lying over the water 



