10 MK. BERKELEY ON THE POTATO MURKAIN. 



is, I think, clearly something different, occurring on the stalks, 

 and not on the tubers. In this disease the tubers, though ap- 

 parently healthy when stored, are rapidly destroyed by the 

 fungus. 



Another disease, arising from a very different fungus, is fre- 

 quent, especially in calcareous districts, and is known commonly 

 by the name of the scab, the surface of the potatoes being covered 

 with pustules, which at length become cup-shaped, and are pow- 

 dered within with an olive-yellow meal, consisting of the spores 

 of a fungus. This also has been partially investigated by Mai*- 

 tius, who has illustrated his observations with some characteristic 

 figures. 



Two other diseases are mentioned in the work of Martius, 

 whicli are, however, so imperfectly known, that it is not neces- 

 sary to notice them upon the present occasion. 



In all the cases referred to above, the disease has either been 

 confined principally to some one country, or, if more widely 

 diffused, its effects have not been of such magnitude as to 

 excite any general fears ; whereas, in the present instance, the 

 whole of Western Europe, from Norway to Bordeaux, seems 

 almost equally to have suffered, and the ravages have not 

 been less in Canada or the Northern parts of the United States 

 of America. It is probable that it has existed for some time 

 without attracting much attention : at any rate it is not the birth 

 of one year only, as the advocates simply of atmospheric influ- 

 ence suppose. Dr. Morren* informs us in his admirable little 

 pamphlet that it has been known for two or three years in Belgium. 

 It appeared in the province of Liege in 1842, and on the 24th 

 of March in the following year he laid before a large assembly 

 of landowners its history, and the means of contending against 

 it. Were this testimony by itself, we could not refuse to take it 

 at the mouth of one who has paid so much attention to the sub- 

 ject, and is so intimately acquainted with all the phases of the 

 disease. But the testimony is far from being solitary. In an 

 excellent article in a Lille paper of the 26th of September, kindly 

 forwarded to me by Monsieur Desmazieres, it is stated that the 

 disease of 1845 is identical with that which he described in a 

 Memoir presented in the latter part of 1844 f to the Royal 

 Society of Lille. The volume of the Transactions of that Society, 

 even for 1843, has only just appeared ; I applied therefore to the 



* instructions populaires sur les moyens de combattre et de detruire la 

 maladie actuelle des Pommes de Terre. Bruxelles, 1845. 



t The exact title of the Memoir is ' Recherches sur I'alteration observee 

 dans le tubercule de la Pomme de Terre grise cultivee dans I'arroudissement 

 de Lille en 1844.' 



