142 EFFECTS OF FUNGI. 



over a jar of some preserve, the moulds are 

 said not to appear. The reason is, the oxygen 

 has been consumed which has been essential to 

 the development of these fungi, and, if the 

 fresh air be excluded immediately, they cannot 

 vegetate. Inoculation, also, of plants by fungi, 

 militates against the notion of spontaneous 

 generation. The true cause of their appear- 

 ance is, undoubtedly, the existence in the 

 atmosphere of the sporules as before stated ; 

 and when these find a situation of growth 

 adapted to their nature, they vegetate and pro- 

 duce fungi. 



The injuries we receive from such fungi are 

 incalculable. We have already seen what mis- 

 chief is done by them to our wheat crops. The 

 loss to the possessors of silkworms from the 

 same causes is often immense ; and the dry- 

 rot fimgus, as every one knows, causes exces- 

 sive damage both in our shipping and in our 

 houses. We have, nevertheless, a grand com- 

 pensation in the benefits conferred by the 

 various tribes of fungi in clearing away the 

 evils arising from decomposing organic matter. 

 They do this good effectually by their unparal- 

 leled rapidity of growth, and by the quickness 

 and facility with which they appropriate the 



