180 DISEASES OF FIELD & GARDEN CROPS. [CH. 



artificial light will show what has become of a germ tube 

 from a fungus spore when it has once travelled down 

 amongst the constituent cells of the leaf. If a germ tube 

 of any given fungus is known to have entered a leaf, and 

 a fungus of a totally different nature appears in eight days 

 or two months afterwards upon the surface of the invaded 

 leaf, where is the clear proof that the foreign germ tube 

 really caused the production of the new fungus-growth ? 

 It is certainly not impossible that one may have arisen 

 from the other, but the proofs of a phenomenon so won- 

 derful should be unimpeachable, proofs such as no one 

 could possibly doubt or question. 



The believers in the connection of corn mildew with 

 barberries always recommend the destruction of barberries 

 as a preventive of corn mildew, and Mr. Carruthers, in 

 the paper already adverted to, writes : " The farmer should 

 not permit the barberry to have a place in his hedges or 

 in plantations on his farm." At one time barberries were 

 abundant in Britain, now they are very rare in a wild 

 state, and as a rule only to be seen in single isolated 

 examples. As the former extirpation of the plant has not 

 lessened the mildew of corn in the slightest degree, why 

 then should the remaining few barberry bushes be 

 destroyed, especially when the case of Australia and 

 New Zealand, where, with a total absence of native bar- 

 berries, corn mildew is worse than in Europe, is remem- 

 bered ? In our own country corn mildew is notoriously 

 at its worst in the fen districts, where the barberry is 

 absent in a wild state. The advocates of the connection 

 of the two fungi acknowledge that mildew is perennial in 

 corn ; being so, the ^Ecidium condition on barberries, 

 even if admitted as a condition of corn mildew, cannot 

 be a necessary condition. With the destructive fungus of 

 spring mildew of corn and its supposed jtEcidium on 

 borages, the case is still more striking. There is no 

 need to tell farmers not to allow any members of the 

 Borage family to have a place in their gardens ; it does 



