ioo DISEASES OF CULTIVATED PLANTS 



matured resting-spores of the fungus are deepest down in 

 the tissue, and that these become smaller and younger as 

 the periphery is approached, and that in the outermost layer 

 of cells for the time being the parasite is in a kind of 

 plasmodial condition, very small, and entirely destitute of 

 a thick, chitinous wall. 



The disease is said to have been known to potato-growers 

 in the Liverpool district for some sixteen years past. Its 

 presence was, however, only made generally known in 1901, 

 when Professor Potter and myself simultaneously and unknown 

 to each other sent an account of the disease to the Journal 

 of the Board of Agriculture. Professor Potter stated that 

 the organism causing the disease was Chrysophlyctis endobiotica 

 (Schilberszky) ; I, on the other hand, considered the fungus to 

 be Endomyces leproides (Trabut). It is now evident that both 

 were mistaken in our identification. On the appearance of 

 such discrepancy as to names, I sent a typical specimen of 

 the disease to Dr. Schilberszky, asking him if it was his 

 Chrysophlyctis endobiotica. His reply was that it was not his 

 species, and that it was unknown to him. This letter from Dr. 

 Schilberszky was not kept, hence when the subsequent con- 

 troversy as to names was resumed, the information I have now 

 given could not be used officially, lacking the necessary evi- 

 dence. A very remarkable feature in connection with the 

 parasite under consideration is the entire absence of the forma- 

 tion of periderm as a protection against further encroachment, 

 whereas in other potato diseases periderm is produced on 

 the least encroachment of any outsider. This fact, coupled 

 with the statement in the very brief preliminary notice given 

 by Schilberszky of his potato disease, that crater-like structures 

 are formed, in addition to the formation of periderm, does 

 not tally with what is met with in black wart disease. For 

 my own mistake I can offer no satisfactory explanation. 



For several years persistent attempts have been made to 

 germinate the resting-spores, but without success, until last 

 year when the announcement was made, almost simultaneously 

 by Professor Johnson of Dublin, Professor Potter of Newcastle, 

 and myself, that the resting-spores had been induced to 

 germinate. The two first-named observers recorded the 

 fact in very brief terms, but agreed that uniciliate zoospores 

 were liberated. In my own case the resting-spores were 

 nine months old when they germinated. A crack appeared 

 in the brown chitinous wall, and the broadly piriform, i- 



