124 FUNGI POISON THE SOIL. 



fertile seasons, rather to the spur given to the general 

 vegetation, which is also communicated to the crypto- 

 gamia, than to a decomposition, which remains without 

 proof, and which, when obviously most active, fails to ex- 

 cite disease. 



As the fungi grow at the end of the phenogamous sea- 

 son, their production depends on causes which may or may 

 not have been felt by the common vegetation. Hence, 

 disease seems in this aspect, of inscrutable origination, 

 unless we look exclusively to the causes which may excite 

 vegetation throughout a season, or only in the spring and 

 summer, or only in the autumn. 



There is a kind of corollary to the last proposition. 

 Places of malarious character often become, at least for a 

 time, quite salubrious, and places which have, for a long 

 course of time, been healthy, unexpectedly and without 

 apparent alterations, acquire morbid conditions. The 

 streams run at their mean height, the pools are filled to 

 their common capacity, the vegetation seems to follow its 

 wonted course; but the health varies according to unseen 

 influences, for all visible and measureable events move in 

 a customary round. These diversities of salubrity are 

 unexplained by the geology, the agriculture, the climate 

 and the meteorology, which, remaining the same, or mov- 

 ing in defined and customary cycles of obvious similitude, 

 leave no evidence of having any effect on the morbid irre- 

 gularities. It would seem as if the unknown cause were 

 migratory, or had long fits of irregular repose. Now, we 

 know of nothing which possesses an acknowledged power 

 of creating febrile diseases, by which such irregularity can 

 be explained, save by reference to the habits of the fungi. 



The cryptogami have, in a high degree, the curious pro- 

 perty of destroying their own reproductive powers, or of poi- 

 soning against themselves the soil in which they grow. The 



