296 DISEASES OF FIELD & GARDEN CROPS. [CH. 



figures both the smooth and echiimlate form on the same 

 plate. Plain and echinulate spores are produced on the 

 same plant in some Saprolegniece ; and Dr. Max Cornu 

 maintains that the Saprolegnia asterophora of De Bary is 

 merely the warted form of Achlya racemosum, Hildb. 

 By the courtesy of the Eev. M. J. Berkeley, we have had an 

 opportunity of carefully examining the original examples 

 found by Dr. Eayer, and described by Dr. Montagne ; and 

 we have no hesitation in stating that they are in every way 

 the same with the bodies found by us on the mycelium of 

 Peronospora infestans, Mont., in 1875. It is useless to re- 

 produce Dr. Montagne's illustration from vol. i. of the 

 Journal of the Royal Horticultural Society, or to engrave 

 his preparations, as they agree precisely with the illus- 

 trations made from fresh specimens, and engraved in the 

 following pages. Dr. Montagne's examples represent 

 fertilised semi-mature oospores, most of the specimens 

 have a smooth external surface, but some of the more 

 mature specimens are spimilose ; and for this reason Dr. 

 Montagne doubtlessly selected the specific name hydno- 

 sporus. 



Dr. Eayer, then, was the first person who in 1844 or 

 1845 detected resting -spores in the genus Peronospora; 

 and the Eev. M. J. Berkeley was the first person who 

 pointed out the fact of Peronospora being an oospore-bearing 

 fungus. Mr. 0. Edmund Broome next found the Artotrogus 

 of Peronospora parasitica, Pers. ; and Mr. Berkeley again 

 pointed out its true nature in the Gardeners' Chronicle for 

 1854, p. 724. In 1845 Tulasne made great advances 

 in our knowledge of the oospores of Peronospora ; and his 

 observations were laid before the French Academy in 

 1854, and published in Comptes Rendus for 26th June of 

 that year. In 1855 Dr. Caspary published still further 

 advances in the Monthly Transactions of the Royal Academy 

 of Berlin ; he there illustrates the oogonia or sporangia, as 

 he terms them, of Peronospora Hepaticce, Gasp., and P. densa, 

 Gasp. Dr. Caspary's observations were, he says, made 



