I. AGRICULTURE AND RURAL ECONOMY. 421 



which penetrates the epidermis, passing rapidly through the 

 leaf, branching and rebranching ; the spotted appearance be- 

 ino- due to the brown colorinor matter contained in its slender 

 root. 



This root, or mycelium, as it is called, sends its branches 

 into the air ; and these are swollen at the extremities, bear- 

 ing minute oval bodies, which are the seeds or the spores. It 

 passes down the leaf-stalk into the stem, and thus reaches 

 other leaves, as also the under-ground branches, and through 

 them the potatoes themselves. In one experiment, spores 

 placed on the leaves of a healthy plant on the 4th of Febru- 

 ary extended over the entire plant by the 9th. 



Such cells as are pierced by the mycelium are destroyed, 

 and the starch granules are consumed ; putrefaction soon be- 

 gins, first affecting the cell-walls, and then the starch. Al- 

 though the minute spores may abound around the diseased 

 plants and on the soil, they never appear to attack healthy 

 plants through the roots, but invariably commence their rav- 

 ages by attaching themselves to the stems or leaves. The 

 proper method of arresting the progress of this disease appears 

 to be the destruction, by fire, of the plants affected, whether 

 leaves, stems, or tubers. If these are left to decay in the 

 field, or get into the manure in the farm-yard, the mycelium 

 or spores will be retained, ready to germinate Avhenever the 

 necessary conditions are present. 



Moisture is indispensable to the germination of these spores, 

 and an excess is always dangerous. Thorough draining is 

 therefore indicated under the circumstances. In conclusion, 

 the report states that there is nothing in one variety of pota- 

 to rather than another to predispose it to attack by the fun- 

 gus, and that, whether the plants be healthy or oth-erwise, 

 wherever the spore rests and finds suitable moisture, it ger- 

 minates. When it has once obtained a footing, its quick 

 growth, during which innumerable spores are developed, 

 causes a rapid advance of the disease. 3 A, July 12, 1873, 41. 



DESTRUCTION OF PHYLLOXERA. 



Tessie du Motay remarks that, among the many proposi- 

 tions for the destruction of the Phylloxera^ or the grape-vine 

 louse, apart from the method of flooding the roots of the vine 

 with water during the winter season, the application of sub 



