16 



and irresistable. In the almost total absence of any reliable 

 information on all points our only alternative is to accept 

 some hypo thesis, founded on the researches of some com- 

 petent authorities. Science is progressive and the opinions 

 of the most able and careful investigators are frequently 

 shown to be founded on error. I have consulted various 

 authorities in vain, and find I have a choice of probabilities 

 but can gain no truly reliable information in regard to tho 

 development of fungoid diseases in plants. The works I 

 have read express the views of Sir Humphry Davy, Fries- 

 Fee-and Bauer, and other diligent investigators and in form- 

 ing my hypothesis I shall adopt their suggestions and believe 

 " that the vapourlike spores of fungi float about in the atmos- 

 *' phere in countless myriads only waiting for the presence of 

 "a fitting soil on which to alight and grow." Fungi may 

 in fact be classed as Nature's nomadic scavengers and 

 are sure to appear and flourish wherever circumstances 

 favoring their development exist. With regard to Leaf Di- 

 sease I shall assume it to be a pest allied to the Undines 

 and shall therefore suggest that it takes its origin in, or 

 that its development is at least favored by, a parasitic 

 soil, that its spores are absorbed by the roots and grow in, 

 the parenchyma of living plants and thus pass through the 

 sap vessels to the leaf. 



In iny next chapter I shall endeavour to justify the 

 course I have adopted. I am perfectly aware I shall be 

 severely reprimanded for choosing this theory, but I can 

 only say, that until something definite is authoritatively 

 given to science I prefer to be influenced by old fashioned 

 ideas than to accept the contradictory propositions which 

 one constantly sees in the newspapers. " Bauer computes 

 " that two million five hundred and sixty thousand individual 

 "fungi (Uredo foetida) would be required to cover one square 

 "inch, and Fries has calculated that each of these individual 

 "plants contain upwards of tea million spores, which areas 



