NATURE OK DISEASE. 141 



Jena, 1900, and, for Boirytis, see Marshall Ward, "A 

 Lily Disease," Afifui/s of Botany, Vol. II., 1889, p. 388. 



The subject of enzymes has been exhaustively treated 

 by Green, The Soluble Ferments and Fermentations, Cam- 

 bridge, 1899, to which the reader is referred for literature. 

 I have taken the statements regarding Fojttaria and 

 DoHum from Kassowitz, Allgenieine Biologie, p. 182. The 

 two most important works on chemotactic phenomena are 

 Pfeffer, " Uber Chemotaktische Bewegungen," etc., Uniers. aus 

 liem Bot. Inst, zu Tubingen, B. II., p. 582, and Miyoshi, " Die 

 Durchbohrung von Membranen durch Pilzfaden," Pringsh. 

 Jahrb. f. Wiss. Bot., B. XXVIII., 1895, p. 269, and from 

 these the further literature can be traced. As regards the 

 nature of parasitism see Marshall Ward, " On Some 

 Relations between Host and Parasite," etc., being the 

 Croonian Lecture dehvered before the Royal Society, 

 Proc. Roy. Soc, Vol. 47, p. 393. On Symbiosis, see 

 Marshall Ward, " Symbiosis," Annals of Botany, 1899, Vol. 

 XIII., p. 549, where the literature is collected. For a 

 general account of galls the reader may consult Kerner, 

 The Natural History of Plants, Eng. ed., 1895, Vol. II., 

 pp. 527-554, and Adler, Alternatitig Generations, A Bio- 

 logical Study of Oak Galls, etc., 1894. 



