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in another way ; in most houses it is usual to throw away diseased tubers, along 

 with parings and other rubbish, into dust heaps, which are in due course carted 

 away, and used as manure ; it is probable that storing potatoes in the same buUding 

 or floor, year after year, favours the spread of the disease. 



Mr. Worthington Smith's discovery teaches that every part of an infected 

 plant should be bimit ; it is the only way of efifectuaUy destroying the fungus ; and 

 also, that under no circumstances should potatoes be planted for two consecutive 

 years in the same ground. 



Parasitical fungi, not content with damaging com and potatoes, are also 

 very injurious to garden produce ; cabbages, beans, peas, celery, and onions, each 

 of them cherish and foster some unbidden visitor— fruit trees, as pears, plums, 

 peaches, filberts, and walnuts, furnish a residence for some unwelcome intruder. 



Flowering plants, gro^vn for their beauty, are much injured, and sometimes 

 killed by parasitical funguses, witness the rose trees and holj^hocks; two years out 

 of three, hopyards are rendered unproductive by the attacks of an Erysiphe. 



Timber trees do not suffer much while in g^rowth, yet it is curious to number 

 the varieties of fungus found on them. M. Wessendorf says, " That 74 attack the 

 lime, of which 11 reside on the leaf ; 114 the spruce fir, and no less than 200 the 

 oak ; " among the latter are reckoned those funguses whose ravages in timber-built 

 ships have occasioned a loss in fourteen years, estimated at twenty millions, and 

 which, in church and domestic architecture, produce great annoyance and expense 

 by causing dry rot. MeruUus, Lachrsrmans, Polyporus, Hybridus, and a Thele- 

 phora are the funguses which prey on sound timber ; their mycelium creeps 

 between the cells, and decomposes tbe lignin and cellulose ; the Merulius has a 

 rusty-coloured, irregular, stemless pileus, from whose giUs a liquid constantly 

 exudes. 



If the useful plants of other countries are examined, we find in the south of 

 Evurope, olives, oranges, and onions damaged by a fungus that envelopes their 

 leaves in a covering of soot ; in the Atlantic isles and France, the Ordium Tuckeri 

 destroys the grape-^dne. This fungus first appeared in an EngHsh hot-house, and 

 thence has spread in all directions. Our friend, M. Comu, told us, last October, 

 that another fungus had lately appeared on the vine at Narbonne, causing a 

 disease called Anthracnose. In some parts of Italy, the cultivation of the silk- 

 worm has been suspended because it is attacked and destroyed wholesale by a 

 species of mould, somewhat resembling that which kiUs flies in the autumn, and 

 leaves them adhering to the glass in our windows, surrounded by a cloud of white 

 spores ; in America the maize is often much injured by a smut that causes large 

 and curious distortions of the grain and cobs. The plant which of all others is the 

 most important for clothing purposes — the cotton plant — has two formidable 

 enemies ; one attacks the leaves, the other the pods. 



Some manufactures are much impeded by the growth of moulds. Bleaching 

 cannot be carried on in the fields, on account of moulds growing and causing un- 



