" COEKY- " OR " POWDERY-SCAB " IN THE POTATO TUBER. 529 



of tlie organism given by Walleoth and Martius which Horne cites 

 are insufficient to estabhsh the- identity of the organism with which 

 -they were deahng, but in any case had Horne been acquainted with 

 Wali .roth's description and figures in the Beitrdge he could scarcely 

 .have come to any other conclusion than that the organism we now call 

 Spongospora was indeed being dealt with. It may be pointed out, 

 •perhaps, that the question of identity does not rest merely upon the 

 degree of accuracy with which the spore-balls are figured, but some 

 . regard must also be paid to the very full description given by Wallroth 

 of the development and fate of the warts, which agrees fully with what 

 we know of the behaviour of Spongospora, and which does not apply 

 to any other organism known at present. It is extremely difficult 

 to concur in Horne 's remarks on Martius 's figures; to me at any 

 rate it is impossible to interpret them as applying to any organism 

 other than Spongospora, and we have it on Martius 's own authority 

 that his organism was identical with that described by Wallroth. 



Berkeley's figures are distinctly poor and not quite accurate (he 

 admits, as has been pointed out, that he had not properly studied the 

 organism), and his specific description published in 1850 is. meagre; 

 but Johnson's demonstration of the identity of the organism in 

 Berkeley's type specimen with the modern Spongospora renders 

 critical remarks rather superfluous. It is, I think, extremely unlikely 

 that Berkeley could have confused the spore-balls oi Spongospora with 

 such structures as the " cell-balls " figured by Horne. 



Horne says " It seems more desirable to retain the name Spongo- 

 spora Solani given to the parasite by Brunchorst, than to adopt first this 

 and [then] that name, as each probing of the older literature of the 

 subject brings to hght some new fact." 



Few workers, however, who accept priority as the basis of nomen- 

 clature, will feel themselves able to concede this point, and it may not 

 be inappropriate at this juncture to quote the following from Article 50 

 ■of the " International Rules of Botanical Nomenclature " : — " No one 

 .i& authorised to reject, change", or modify a name (or combination of 

 names) because it is badly chosen, or disagreeable, or another is pre- 

 ferable or better known, or because . . i" 



Unless, therefore, further probing of the fiterature between 1842 

 and 1753 should show (which I think is most unlikely) that this organ- 

 ism had already been described and named, the specific name of it 

 must (in accordance with the International Eules) be that of its 

 (Driginal describer Wallroth — namely, suhterranea. 



Massee,! who adopts the name Spongospora scabies for the organ- 

 ism, states: "Some people profess to trace the name back with 

 certainty to much older authors [than Berkeley] on the strength of 

 retrospective synonymy, but Berkeley's description and figure is the 

 oldest that enables anyone to be certain as to the fungus he had in 

 view." I have already pointed out (and in this respect am in agreement 



* The italics are the present writer's. 



t Massee, Diseases of Cidtivated Plants and Trees, London, 1910, p. 528. 

 VOL. XXXVIII. M M 



