develop themselves w^liich liave the fomi of eggs. 

 but which have not more than the hundredth 

 ipart, or even less, of a millimeter hi size. I 

 may be told it is a vcrj- small body to commit 

 ravages so great ; but I answer, the itch is not 

 tlie less to be feared because the animalcule 

 which produces it is a microscopic being. 



"After the formation of the yellow spot, and the 

 de^velopment of the 'botrydis' on the leaf of the 

 Potato, the stem receives the deleterious influ- 

 ences. Here and there its surface becomes 

 brown, blacken.s, and when the phases of the 

 evil are followed with the microscope, it is soon 

 perceived that the stem is attacked through the 

 bark. The morbid agent carries its action from 

 the bark to the skin, and although this does not 

 always offer mushroom.s, it is not the less strick- 

 en with death ; for to any one that has some no- 

 tions of vegetable physiology these effects 

 easily explain themselves. The sap modified 

 into living juice, into vegetable blood, forms 

 itself in the leaf, and then descends into the stem 

 and the root, by the bark. Here this sap is 

 sick, modified, it carries the poison of the leaf 

 into the stem, and this perishes. Indeed, so 

 soon as the black spots declare themselves on 

 the stems the leaves become dry and die — 

 blackened and stricken with death by a ven- 

 omous mushroom, they fall, unfortunately, to 

 pro n agate the source of the scourge, or to de- 

 posit its germ in the earth. I will soon indicate 

 the means which should be taken, to prevent 

 this fatal communication. 



" The infection soon descends into the tubercle 

 Itself. If the evil follows its course, the tuber- 

 cle immediately gangrenes. A Potato is not a 

 root, but a branch ; it follows from that, that a 

 tubercle possesses a marrow which is the eata- 

 ble part to be prefcn-ed, and a distinct bark. 

 Between the marrow and the bark is found a 

 zone of vessels which represents wood. One 

 can easily understand this structure by cutting 

 a thin slice of Potato and placing it betvi'een the 

 eye and the light. Now the infection attacks 

 the part which receives the descending sap, that 

 part where the morbid agent has itself descend- 

 ed. Upon a Potato attacked, one perceives a 

 series of livid spots, brown or yellow, some- 

 times grey or blackened — a series which ex- 

 tends itself throughout the woody zone. In fol- 

 .lov7ing the progress of the evil over a great 

 .imEiber of spoiled tubercles, I could see how 

 the dLsease, increasing by small degrees, fin- 

 ishefi by reaching the heart itself of the Potato, 

 and corrupts it entirely. The skin of the sick 

 Potalc easily detaches itself; the flesh no longer 

 cracks under the knife ; a discolored flacidity, a 

 fade, ard, later, an animal smell, analogous to 

 that of mushroom freshly cut, declares itself and 

 , earries bfi the heart. The animals even refuse 

 : to eat a focd which may be regarded to be quite | 

 (800) 



as injurious as deteriorated mashrooms them- 

 selves. 



" So soon as the Potato is gangrened within, 

 that is, in its cortical part, but a few days, three 

 at the most, are sufficient for the mu.?hroom (the 

 • botrydis ') to show itself without. This white 

 efflorescence is seen to declare itself in the eyes 

 of the tubercles, and then extend itsell' 1 ke light, 

 white flakes, at first upon a rounded surface, but 

 which finishes by invading the whole tubercle. 

 The Potato is then entirely lost. 



" The source of the evil being known, all the 

 attention of the cultivator should be directed 

 toward the destruction of the mushroom ; for it 

 is unfortunately too true that the blight, the rust, 

 and all the race of para.=itesonce introduced into 

 the country-, they remain there and propagate 

 themselves. This year the epidemic has been 

 general ; every where the geiTns of it exist ; 

 millions of that which propagate it, if their 

 number be not diminished, will attack the 

 plants the approaching year, and it will then be 

 more difficult than ever to eradicate the plague, 

 to do which it is essential to adopt the following 

 means : 



" 1st. When the leaves are lost they must be 

 collected as quickly as pp.ssible, and burnt upon 

 the spot, without being transported to a dis- 

 tance. The aphes may be spread upon the soil. 

 In collecting them they must be shaken as little 

 as possible. I have seen, with regret, the 

 farmers collect the sick leaves to preserve them 

 in a pile in the field, or to cast them over the 

 hedges. This is to preserve the plague for the 

 next year. 



" 2d. When certain varieties of the Potato, or 

 certain localities are free from the calamity at 

 the time of the crop, it is always prudent to 

 burn the leaves ; for a field may appear clear of 

 the ' botrj-dis ' when it is not so. Several leaves 

 are attacked ; these leaves throw out the seeds 

 of the disease upon the tubercles, which, pre- 

 served as seed will preserve the disease the next 

 year. 



"3d. If the tubercles are themselves attacked, 

 it is essential to take them out of the earth to 

 make a prompt choice out of them, which is 

 easy, for habit soon enables one to recognize 

 the spoiled tubercles from those which are not 

 so. The sound tubercles ought to be used as 

 soon as possible, for they are not injurious up » 

 the moment the bark becomes yellow. The 

 smell alone is sufficient to detect the develop- 

 ment of the malady. The sick tubercles should 

 be burned. 



" 4th. To obviate the sorrowful consequences 

 of a crop which will be always reduced either a 

 half, or a third, or even less, than an ordinary 

 crop, it would be important to follow, in onr 

 country, the method pi-acticed in Scotland in 

 cultivating Potatoes during winter. 



