108 



The Potatoe Disease. 



Vol. XL 



The Potatoe Disease. 



As the season approaches when the rav- 

 ages of this disease generally make their 

 appearance, it is desirable to know how far 

 investigations already entered into, have 

 proceeded towards the detection of the 

 cause of such an evil, and the suggestion of 

 a remedy. Little has as yet been done on 

 any organized plan in this country. In Eu- 

 rope, the case has been very different. In 

 Holland and Belgium a committee was first 

 appointed to collect facts calculated to throw 

 light on the nature of the disease. In one 

 of the Dutch provinces, Groningen, a sepa- 

 rate commission was appointed for the same 

 purpose. 



In Germany, Liebig among others has 

 turned his attention to the potatoe, and has 

 lately published some observations on its ni- 

 trogenous constituents. 



A number of the French philosophers, 

 both alone, and under the auspices of the 

 Central Society of Agriculture, have also 

 attended to the subject. M. Payen has 

 lately published three or four reports con- 

 taining the results of elaborate microscopic 

 and chemical researches. 



The English government sent a commis- 

 sion to Ireland, of three distinguished scien- 

 tific men, with directions to obtain as much 

 information as possible on the nature and 

 extent of the disease. In Scotland origi- 

 nated the most extended scheme of all. 

 The subject was taken up in its several 

 branches, as it is connected with botany, 

 meteorology, entomology, and chemistry. 

 Each branch was referred to a competent 

 person, and the investigation is still in pro- 

 gress. 



It is not, as yet, even certainly determined 

 in what form the disease first attacks the 

 plant. A great number of observers have 

 considered that it is first seen in patches of 

 dark coloured fungi on the leaves, thence 

 gradually spreading down to the tubers. 

 Dr. Ferguson, in Paris, and several others 

 in England, think that they have detected 

 the sporules of the fungus passing down 

 through the stem in the ordinary circulation 

 of sap. But there are well authenticated 

 instances where the potatoe tops have re- 

 mained green and flourishing while the tu- 

 bers were much diseased ; it cannot, there- 

 fore, be said with certainty that the disease 

 first appears as a fungus on the leaves. 



All agree that the nitrogenous compounds 

 in the tuber are afi^ected first, and to a pecu- 

 liar state of these constituents, Liebig and 

 others have referred the origin of the dis- 

 ease. The starch is attacked last, and often 

 remains uninjured when the walls of the 



cellular tissue that enclose its globules are 

 nearly destroyed. From potatoes which 

 have become even offensive in their smell, 

 perfectly good starch has been extracted. 

 The manufacture of starch becomes of great 

 importance in the economical disposition of 

 the diseased potatoe. 



The report of the Groningen commission 

 ascribes the disease to the wetness and sud- 

 den changes of the two last years. M. 

 Payen thinks that excessive moisture has 

 predisposed the potatoe to yield to the at- 

 tacks of fungi. Mr. Phillips, of London, 

 has published a pamphlet, in which he as- 

 cribes the whole thing to the same cause. 

 These are only a few of those who advocate 

 this view of the question. All who have 

 experienced much rain, assign this as the 

 cause of disease, not knowing that it has 

 been quite as bad on dry soils, and where 

 there has been little rain. In all the west 

 of Scotland, the summer of 1845 was consi- 

 dered rather a dry one, and in Islay, one of 

 the western islands on the Scotch coast, the 

 streams had not been so low for many years. 

 The potatoes were as much affected in this 

 part of Scotland as on the east coast. These 

 facts seem quite decisive on the subject of 

 wetness, for one well authenticated case 

 where the disease has occurred under cir- 

 cumstances that preclude the idea of its 

 being caused by wet, renders the theory 

 quite untenable. 



It is not so easy to decide whether atmos- 

 pheric influence is the cause of the disease. 

 In order to arrive at any certain conclusion 

 on this point, extended meteorological obser- 

 vations are necessary. It is a singular fact 

 that three or four counties forming the ex- 

 treme northern point of Scotland were en- 

 tirely free from it, without any essential 

 difference in their season from that of the 

 other counties, so far as was known by or- 

 dinary observers. The overseer of Mr. 

 Fleming, of Barochan, in Renfrewshire, 

 Scotland, lifted froni one of his fields, on 

 the 5th of September last, 1845, about five 

 hundred weight of potatoes; these were 

 stored in the house and remained perfectly 

 sound at the date of his writing, in the mid- 

 dle of winter. From the same field on the 

 15th of September, were lifted five hundred 

 weight more of the same potatoes. These, 

 after being in the house two days, were 

 tainted and decaying, as was the case before 

 the end of Septeniber with all that were left 

 in the field. In this instance, the crisis in 

 Ihe change from the healthy to the diseased 

 tuber took place between the 5th and 15th 

 of September. If the disease had shown 

 itself at this time simultaneously in every 

 part of that district, this fact would go far 



