Host and Parasite in certain Diseases of Plants. 42 & 



of many fruits, such as pears and apples,* grapes,f cranberries, J &c. r 

 and on chestnuts. § In short, even the forms of JBotrytis which were 

 most persistently regarded as saprophytic have now been shown to- 

 enter living plants and cause parasitic diseases in them,|| and com- 

 plaints of such epidemics are occasionally heard from various parts, 

 as a rule, however, the disease is sporadic, and I now proceed to- 

 describe its symptoms. 



!FiG. 8. A bunch of "mouldy" grapes infested with Botrytis*. einerea. The 

 ravages of the fungus cause the skin to rupture, and the fruits to shrivel from 

 loss of water ; other changes in the substance of the contents are referred to in. 

 the text. Patches of the conidiophores are seen on the exterior (Muller- 

 Thurgau) . 



Small reddish-brown spots appear on the leaves, pedicels, ripening 

 fruit, or other organ attacked ; these enlarge and spread, and the 

 parts turn brown, shrivel up, and rot off or dry up, according to the 

 state of the weather. In some cases the whole plant gradually turns 



* Sorauer, ' Pflanzenkrankheiten,' vol. 2, p. 298. 



f See especially Muller-Thurgau, in Thiol's ' Landwirthsch. Jahrb.,' vol. 17, 

 1888, pp. 83—160, on " Edelfaule." 



X See especially Woronin, ' Mem. de 1' Acad, de St. Petersb. ,' vol. 36, No/ 6, , 

 1888. 



§ Kissling, ' Zur Biologie der Botrytis cmerea,' Bern, 1889, p. 14 (where also the 

 literature is collected). 



|! JE.g., JB. cinerea, the conidiophores of Peziza Fuckeliana (see de Bary, ' Comp. 

 Morph. and Biol, of Fungi,' p. 380), is now known to be^capable M of producing 

 epidemic diseases in vines, gentians, &c. 



