Johnson — Chrysofhlyctis endobiotica and other Chytridiacece. 137 



by warty seed-tubers, which, I think, accounts for the outbreak of black wart 

 in Co. Down. Kilkeel, one of the disease-spots, is an important fishing- village 

 on the coast, with considerable intercourse with the English and Scotch coasts, 

 from which slightly diseased tubers could easily be imported, unnoticed by 

 the buyer. 



The warty disease was reported from Germany in the autumn of 1908, 

 and is now known from various districts in Westplialia and tlie Rhine 

 Provinces. It would appear from reports in the Deutsche LandwirtsehciftUche 

 Presse (30th Sept., and 17th Oct., 1908), and the Illiistrirte LandioirtschaftUche 

 Zeitmig (2nd Dec, 1908), copies of which I have received from Dr. Riehra, that, 

 as in Cheshire so iu Germany, the disease was left unnoticed and unreported 

 for several years before tlie attention of botanists was called to it as an 

 increasingly troublesome pest. The tendency in Germany, judging from the 

 articles, is to regard the disease as not very serious, since it is confined, it is 

 stated, to small garden-plots, where potatoes are grown year after year in 

 the same ground. Germany would make a serious mistake if it treated the 

 outbreak of the disease with indifference. Tiiis, I know, its mycologists will 

 not do. It needs only a veiy casual acquaintance with the facts of the case 

 in the British Isles from the time of the discovery of the trouble by Potter 

 in 1902 to the present time to warn one of the necessity of taking all 

 possible steps to stamp out a disease which may become as serious as 

 ordinary leaf-blight, and less amenable to treatment.^ The soil, manure, 

 and weather are not considered in Germany as predisposing causes. Tlie 

 disease, most marked in the variety Magnum Bonum, called locally Stupmoll, 

 is attributed solely to want of rotation in the crops. It is called locally 

 canker," and is believed to induce cancer in eaters of diseased tubers. There 

 is no evidence of this connexion. 



Affinities. 

 Ghrysojjhlyctis endubioHca is a member of the group Olpidiaeese, and is 

 allied to Asteroci/stis radicis. Massee regards it as a Synchytrium, basing 

 his opinion on : — 



(a) The epidermal nature of the parasite. 



(b) The presence of an enveloping membrane round tlie protruding 



contents of the sporangium. 

 I have already shown that, tliougli the parasite may enter the potato, in 

 some cases, at the epidermis, it is not its only seat, and tliat it may occur iu 

 a deep-seated position, even below the cork. 



' The only redeeming feature iu connexion viith the disease is that its germs do not, so fiir as we 

 know, spread aerially in the growing crop. 



'' In some parts of England it is called "cauliflower." 



