330 Notes on Mildem^from 



has tried many experiments respecting its cure. Hawthorn 

 trees are attacked by a fungus, which at first appears merely 

 a point made by an insect, but afterwards looks like fungi 

 (^cidium laceratum Bee). [See Vol.VIII. p. 179. and 739.] 

 The sycamore fungus is a black spot consisting of oblong 

 purplish bodies, yellow inside, and containing tubes filled 

 with seeds, ^cidium Grossularise Dec. {Jig. 91.) attacks 

 gooseberry bushes, and iEcidium cornutum {Jig. 94.) the 

 mountain ash : both spread rapidly, and are very difficult to 

 cure. The ergot on the rye is a well-known and very de- 

 structive species of mildew. It partakes of the nature of the 

 truffle, and grows out of a spike of corn like a prolonged 

 kernel. It is long, horny, and cartilaginous ; and it consists 

 of fibres closely interlaced. This disease evidently originates 

 in the centre of the stem. It affects maize, various species of 

 grass, and is often found in plants of yellow gentian, &c. 



The principal fungi of the third class, or those which 

 attack the roots of plants, are two ; and both closely resemble 

 truffles. One of these (Rhizoctonia Crocorum) {^g. 98.), 

 which is of a brownish yellow, attacks 

 crocuses ; and, in those countries where 

 the crocus is cultivated for its saffron as 

 an article of commerce, it makes great 

 ravages. It is called by the French 

 la mart du sqfran^ and soon destroys a 

 whole crop. The other fungus, PericMa 

 tomentosa, is found on the potato, 

 lucern, &c. It turns the roots, which 

 are naturally white, of a purplish hue. 

 Its ravages are often attributed to grubs. Both these fungi 

 appear to be propagated by spawn, or fibres which spread 

 thi'ough the earth, and cling round the roots which they find 

 in their way. 



Having given a rapid sketch of some of the principal kinds 

 of fungi which produce mildew. Dr. Lindley proceeded to 

 speak of the causes which produce them, and of their cure. All 

 are very easily propagated, from the rapidity with which they 

 arrive at maturity, and the immense number of seeds which 

 they produce. Most of the mildew fungi require only tw^enty- 

 four hours from the first springing of the plant to the ripen- 

 ing of its seed ; and the number produced by each may be 

 ffuessed from the circumstance of one mushroom beinor suf- 

 ficient to propagate 250,000,000. The extreme minuteness 

 of the mildew fungi renders them still more numei'ous. The 

 first class, or the superficial mildew, appears to be com- 

 municated by the air, the seeds when ripe being carried by it 

 from one plant to another, and establishing themselves wher- 



