22 MISTAKES SrECULATIONS. 



all the natural productions called by the com- 

 mon name of fungi. Some which have been 

 long regarded as fungi are merely blisters of 

 acm-i^ or plant-lice ; they are found on leaves of 

 pear-trees, and, till examined carefully, would 

 easily mislead the observer. Others, as for in- 

 stance those bearing the name of erineum, are 

 only diseases of the superficial tissue of the 

 leaves where they make their appearance. It is 

 very essential, therefore, that we should show 

 that diseases of plants attributed to fungi do 

 actually proceed from them. 



As may be conceived, speculations upon 

 the fungi have been not a few. They have 

 arisen out of their rapid growth, meteoric cha- 

 racter, the increase of species under certain 

 circumstances, the development of parasitic 

 fungi only on particular parts of plants and 

 nowhere else, and many other ascertained facts. 

 But it is best at once to state, that the only 

 truth-like solution of their source is the almost 

 universal diffusion of their inconceivably small 

 sporules, which are so numerous and minute, 

 that it is not easy to conceive any place where 

 they may not abound. They are ever at hand, 

 only awaiting suitable conditions for spring- 

 ing up into existence. 



