CONTEIBUTIONS FROM THE WISLEY LABORATORY. 381 



bodies found associated with another Hyphomycetous fungus. In 

 another case, balls of blackish spore-like bodies were formed in a some- 

 what similar manner, except that differentiation into two kinds of cell 

 was not observed. Figs. 104 k-o illustrate the stages in development. 



In Johnson's paper, entitled " Further Observations on Powdery 

 Potato Scab," a comparison is made between a figure reproduced from 

 Maetius' work. Die Kartojfel-Epidemie, and one of Brunchorst's 

 figures. These figures relate to sections of potato containing Proto- 

 myces (Martius) and Spongospora (Brunchorst), respectively. This 

 comparison, however, explains nothing at all. Appearances resembling 

 those represented in Martius' figure (Plate xii., fig. 2, Johnson) are 

 often seen in diseased potato tissues which are not affected with 

 Spongospora. Brunchorst's figure (Plate xii., fig. 3, Johnson), 

 however, undoubtedly conveys the idea that abnormal cell formation 

 is taking place locally. 



If reference be made to Die Kartoffel-Epidemie,\ and especially to 

 the illustrations, it will be seen that the latter relate to 

 several organisms. Figs. 34 and 35 of Martius represent starch 

 grains, wh^ch are corroded as if by the action of Phellomyces ; fig. 5 

 represents a tuber affected with ''dry rot" {Fusarium solani). 

 Figs. 3, 4, and 5 are suggestive of Fusarium. Figs. 9, 10, 19, and 

 25 (Protomyces) are unconvincing. The bodies figured are angular 

 and irregular in contour, whereas the spore-balls of Spongospora are 

 rounded and generally possess a regular outline. Since the starch 

 grains (figs. 34 and 35) are fairly accurately represented, it is not so 

 easy to believe that the drawings of Protomyces were really made 

 from Spongospora spore-balls. Figs. 36 and 37 {Protomyces) might 

 represent Spongospora. 



Johnson :|: states that the first account of the scab fungus is given 

 by Wallroth in Linncea, 1842; that Martius saw Wallroth's pre- 

 parations and description, and agreed with him as to the nature of the 

 organism; that Martius transferred the fungus to the genus Proto- 

 myces, and gave an amended diagnosis of it — this was in Die Kartoffel- 

 Epidemie. 



Wallroth 's§ description, which is very short, and without illus- 

 trations, was written February 15, 1842. It was pubhshed in Part 3 

 of LinncEa for that year. Since this part contains papers written in 

 June, the actual date of publication must have been later. The disease 

 was mentioned by Martius 1| in a paper overlooked by Johnson, read 

 before I'Academie des Sciences on August 16, 1842, published in 

 Comptes Rendus, No. 7 (1842), and abstracted in Annales Science 

 Naturelle. In these publications the organism is referred to as a 

 Protomyces. It is probable that a very short interval elapsed between 

 the date of publication of Wallroth's technical description in Linn^ea 

 and Martius' paper. It would thus be difficult to determine which 



* T. Johnson, I.e. p. 169. t C. E. P. von Martius, Ic. 



t T. Johnson, I.e. p. 168. § F. W. Wallroth, I.e. 



11 C. E. P. voN Martius, Comptes Bendus, xv.. No. 7 (1842), p. 314. 



