xxxvi.] POTATO DISEASE, II. PASSIVE STATE. 313 



Artotrogus from Professor de Bary's own hand ; it shows 

 the septate mycelium at AAA, the supporting thread of 

 the oogonium at B, and the distinct supporting thread 

 (not anatomically connected) of the antheridium at C. 

 At D the antheridium has projected a fecundating tube 

 through the outer wall of the oogonium to the oosphere 

 within. Professor de Bary found these bodies in 

 Lepidium, so they cannot be the true Artotrogus hydno- 

 sporus, Mont, which is borne only on the mycelium of 

 Peronospora infestans, Mont. They are the second form 

 of Artotrogus, peculiar to cruciferous plants, as first 



B 



X-400 



Fio. 137. 



Artotrogus, as illustrated by Professor De Bary in 1881. 

 Enlarged 400 diameters. 



detected by Mr. C. Edmund Broome, M.A., F.L.S., of 

 Batheaston, Bath, in. 1849, and referred to Artotrogus by 

 Dr. Montagne. They grow upon the mycelium of 

 Peronospora parasitica, Pers., and are the oospores or 

 resting-spores of the putrefactive fungus of the cabbage 

 tribe, as pointed out by the Kev. M. J. Berkeley in the 

 Gardeners' Chronicle for 1854, p. 724. They are illus- 

 trated, from nature, in this work in Figs. 31, 37, and 38. 

 No agricultural subject is more difficult to approach 

 than the possible curative or preventive treatment of the 

 potato disease. Cure, we may say, is utterly impossible, 



