CHAPTEE XXXVI. 



POTATO DISEASE, II. 

 Peronospora infestans, Mont. 



ITS PASSIVE STATE. 



WE will now closely examine the bodies found in spent 

 potatoes by Dr. Rayer, illustrated by Dr. Montagne in 

 1845, and described by the Eev. M. J. Berkeley in vol. 

 i. of the Journal of the Royal Horticultural Society, 1846. 

 Dr. Montagne termed the bodies discovered by Dr. 

 Rayer in the intercellular passages of potatoes, Artotrogus 

 hydnosporus. The generic name is derived from the 

 Greek artos, bread ; and trogo, eating or consuming, and 

 bears reference to the power of the fungus in consuming 

 the nutritious material of the tuber ; the name shows 

 that Dr. Montagne suspected the true nature of the fungus. 

 Hydnosporus indicates that the spores resemble the fungus 

 named Hydnum, which has its fruiting surface covered 

 with spines or prickles ; Hydnum is from the Greek hud- 

 non, a word used by Theophrastus to denote a truffle. 

 The specific name is somewhat misleading, as it was only 

 meant to refer to the mature spores, as is proved by the 

 writing on Dr. Montagne's original drawing, see page 

 84 ; and the description of Mr. Berkeley's plate, Journal 

 of the Royal Horticultural Society, 1846, p. 34. In 

 infancy Artotrogus is smooth spored. No phenomenon 

 is better known in fungi, as in Cystopus and the Gas- 

 teromycetes, than a smooth oogonium or spore becoming 

 warted or spinulose with age ; and Mr. Berkeley, in the 

 volume above quoted, from Dr. Montagne's examples, 



