326 VEGETABLE SUBSTANCES. 



In the economy of nature the fungi are the at- 

 tendants of decomposition. Their seeds are too 

 minute for the eye, or even for the microscope, and 

 therefore may be present everywhere undetected in 

 the vessels, the fluids, and probably the solids of 

 plants and animals. The instant vitality ceases in 

 these, the seeds of the fungi come into action. Ac- 

 cordingly they are most abundant during autumn, 

 in rank and shady places, and in rainy weather, when 

 decayed plants and insects may be presumed most to 

 abound. 



This class of plants is still very imperfectly under- 

 stood, and the phenomena attendant on their growth 

 cannot be explained. It has been found, by fatal ex- 

 perience, that some species, which are not poisonous 

 when they grow upon an open and dry champaign, 

 become so when they meet with stagnant water, 

 putrescent plants, and dead insects. 



The kinds which are used as esculents in Britain 

 are principally the truffle, the morel, and some spe- 

 cies of mushroom; but in other countries, and espe- 

 cially in Russia, most species are eaten, even those 

 which in Britain are the most poisonous, or at least 

 the most acrid. 



What the poison in fungi may be has not yet been 

 accurately ascertained. Some of the boleti, which 

 have the under sides of the caps formed of tubes 

 instead of gills, yield even spontaneously crystals of 

 oxalic acid, and others, as the champignon, are sup- 

 posed to contain prussic acid. According to the 

 analysis of Braconnot, fungi contain two peculiar 

 substances, fungin and boletic acid. The nutritive 

 part seems to reside in the fungin, and the poison 

 and flavour in the acid, or at least in the juices of 

 which the acid forms a part. Fungin is white, soft, 

 and insipid; when burnt it smells like bread, and by 

 distillation it yields a brown oil, water, ammonia, 



