INTRODUCTORY OBSERVATIONS. lix 



iftence of certain fpecies of aquatic mould that are. 

 not to be found on terreftrial fubltances. 



Mould is fometlmes feen in nuls and other Ihell 

 fruit, without any vifible opening. In this cafe, 

 it has, perhaps, penetrated the parts of fruftifica- 

 tion in an early ftage, or while the plant was in. 

 flower ; for it is unlikely that the feeds, how- 

 ever minute, will penetrate a thick fhell where 

 pores do not abound. They may lie in the fruit 

 till an opportunity occurs for their develope- 

 ment. Thefe examples, it is true, are attended 

 with great difficulty ; but there are certainly me- 

 thods of explaining them, though ftill undif- 

 covered, unlefs we recur to equivocal generation, 

 which is abfurd. 



Another theory may, be conceived, which is the 

 moil probable of any. The feeds of mould may be 

 difleminated in fuch abundance as to enter intO' 

 the compofition of all animal and vegetable fub- 

 ftances. They find a receptacle in the external 

 pores, or enter within the body itfclf. If a flice 

 of moiftened bread is put under a very fmall re- 

 . ceiver, it will foon be covered with as many 

 plants as would require miUions of feeds for their 

 origin. Six fquare inches of flour and water 

 boiled into pafte, ana put under a receiver, not 

 above eleven or twelve inches in capacity, have 



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