194 Seientiftc Proceedings, Royal Dublin Society. 



Eeeent investigations of the genus Fusarium, particularly those of Appel 

 and Wollenweber, 1 have, however, shown that very great confusion prevails 

 in the ealier literature as to what fungus is really and correctly represented 

 by the name Fusarium (Fusisporium) Solani. It appears that the specific 

 name Solani has been applied at one time or another to no less than nine 

 distinct species of this genus ; and even the original Fusisporium Solani of 

 Martius proves to be a name which includes two distinct species, and these 

 Appel and Wollenweber name Fusarium Solani (Martius pro parte) and 

 Fusarium Martii (n. sp.). 



This being so, it seemed eminently desirable to make a renewed study of 

 the fungus causing the dry-rot of the potato in this country, with a view to 

 ascertaining its exact identity, and whether only one species commonly 

 causes the rot. This was all the more necessary in view of the fact that this 

 disease of the potato has received an increasing amount of attention on the 

 part of phytopathologists in recent years, notably in the United States of 

 America ; and it was important to know whether the prevalent dry-rot- 

 producing organisms were identical on the two continents. 



Before dealing with the further investigations which we have made 

 concerning the disease, it is necessary to give a review of the literature on 

 the subject which has been published since the appearance of the previous 

 paper in 1908. 



II. — Previous Literature. 



In 1909 Miss Longman 2 published a description of the disease as it 

 occurs in the south of England. Two types of fungus pustules are described 

 as occurring on naturally affected tubers, viz. :— (1) those consisting of small 

 tufts of hyphae bearing typical Fusarium conidia, usually white or buff- 

 coloured, but sometimes pink ; and (2) those in which the conidia are at first 

 enclosed in a structure having a thin wall made up of closely interwoven 

 hyphae, this wall being sometimes buff-coloured, but more often pink. Some 

 of these structures possess no openings, but others have an apical pore, and 

 are regarded by Miss Longman as being pycnidia. Owing to the production of 

 these structures, the authoress proposed to remove the fungus from the genus 

 Fusarium and place it in that of Aschersonia Mont. 



Miss Longman states that if potatoes affected with dry-rot are not wholly 



1 Appel, O., and H. W. Wollenweber. Grundlagen einer Monographie der Gattung 

 Fusarium (Link). Arb. Kais. Biol. Anstalt, Bd. viii. Heft 1, 1910. 



2 Longman, S. The Dry-rot of Potatoes. Journ. Linn. Soc, vol. xxxix. Bot. ix. 270 

 1909, p. 120, 



