Spongospora subterranea, (Wallroth) Johnson. 1 
BY 
T. G. B. OSBORN, B.Sc. 
Lecturer in Economic Botany , the Victoria University , Manchester. 
With Plate XXVII. 
T HE organism producing the ‘ Corky ’ or ‘ Powdery Scab ’ of potatoes 
{Spongospora subterranea) has recently been described by both 
Johnson 2 and Massee , 3 but, as the results contained in these investigations 
are not in agreement, further work on the subject seemed desirable. In the 
present paper I shall confine myself to giving an account of the life-history 
and cytology of Spongospora so far as I have been able to trace them, together 
with some remarks on its affinities. Into the disagreement that has arisen 
between the two previous workers on the subject of nomenclature, I do not 
propose to enter. The name I have adopted would seem to be justified on 
the ground of priority , 4 and it is sufficient to refer to the discussion in the 
papers quoted. 
The plants used in this investigation were grown in the experimental 
greenhouses of the Botanical Department of the University of Manchester, 
and I wish to thank Mr. J. M. Hector, of Leeds University, for some of the 
‘ seed 5 potatoes used. The laboratory work has been carried out in the 
Cryptogamic Research Laboratory here, and I should like to express my 
thanks to Professor W. H. Lang for the facilities afforded there, and for his 
kindly interest and help. 
Introductory. 
The disease known as ‘ Powdery Scab ’ or ‘ Corky Scab ’ of potatoes is 
produced by an internally living parasite, Spongospora subterranea , hitherto 
regarded as a member of the Mycetozoa and having affinities with Plastno- 
1 A summary of these results was given in the January number of this Journal (p. 271), and in 
the same number Mr. A. S. Horne gave a preliminary account of his work on Spongospora (p. 272). 
2 Johnson, T. : Econ. Proc. Roy. Dublin Soc., vol. i, pt. t2, Apr., 1908; Sci. Proc. Roy. 
Dublin Soc., vol. xii, N. S., No. 16, July, 1909. 
3 Massee, G. : Journal of the Board of Agriculture, vol. xv, 1908, p. 592. 
4 Erysibe subterranea , Wallroth, 1842 ; redescribed by Brunchorst (who was unaware of the 
earlier description) in 1886 as Spongospora Solani . 
[Annals of Botany, Vol. XXV. No. XCVIII. April, 1911.] 
