MR. BERKELEY ON THE POTATO MUKBAIN. 9 



II. — Observations, Botanical and Physiological, on the Potato 

 Murrain. By the Rev. M. J. Berkeley, M.A., F.L.S. 



Few subjects have attracted more attention, or have been more 

 variously canvassed, than the malady with which Potatoes have 

 been almost universally visited during the autumn of 1845. 

 The press has teemed with notices the most contradictory ; the 

 attention of scientific men in every direction has been engaged 

 by it ; and three, at least, of the principal governments of Eu- 

 rope have issued commissions to examine into its etiology, and to 

 discover, if possible, a remedy. 



It is not indeed the first time that very serious disease has 

 existed in this important article of food : more than half a cen- 

 tury back, cultivators were much alarmed by a disease known 

 under the name of the Curl, which committed at that time im- 

 mense ravages, and is even now, especially in the North, a very 

 formidable evil. It consists in a sudden check of growth in the 

 young shoots, and, in consequence, a failure of produce. As is 

 the case with so many diseases of plants, the cause is very im- 

 perfectly known. 



In 1830 a disease was first noticed in Germany, called, from one 

 of its leading features, the dry rot. For several successive years 

 it was observed to increase in intensity, threatening to put an 

 end to the cultivation of potatoes in the affected districts. The 

 attention of the Bavarian Government especially was called to 

 the subject, and Martins has published an admirable account of 

 it.* The tubers, when stored for winter use or when planted, 

 become impregnated with a kind of mould, and are at length so 

 hard that tliey can scarcely be broken, and, instead of producing 

 shoots, merely throw out a few small misshapen tubers. He 

 attributes it to the growth of a peculiar fungus. 



A somewhat similar disease, but differing in the circumstance 

 that the tubers become soft instead of hard, has certainly been 

 prevalent for many years without attracting much attention, and 

 is probably more or less mixed up with the particular disease to 

 which so much consideration has of late been paid. It is marked 

 by the presence of parasitic fungi, which for the most part appear 

 under the form of hemispherical masses bursting through the cu- 

 ticle, and is referred by Fries to his genus Periola. The earliest 

 record I am at present acquainted with of the existence of this 

 genus is in 1815, in which year it was characterised by Fries, f 

 for the plant of Tode,| to which he refers, published in 1790, 



* Die Kaitoffel-Epidemie. MiinchcD, 1842. 



t Fries, Obs. Myc, vol. i. p. 205. % Fungi Meckl. Fasc. i. p. 6, 1790. 



