358 



BOTANT. 



ing the year 1878, and for a year or two previous to that date, large 

 numbers of salmon and other kinds of fish were destroyed by one of the 

 ■common species, Sapvolegnia ferax.* 



342.— Order Peronosporese. The plants of this order 

 live parasitically in the interior of higher plants. They are 

 •composed of long branching tubes, whose cayities are con- 

 tinuous throughout. They grow between the cells of their 

 iiosts, and draw nourishment from them by means of pecu- 



Fio. 174. 



Fio. 175. 



Fig. 174.— A vegetative hypha, m, m, of Peronomora calotheca from the tissue of 

 Asp&nda saii/va. The two cells between s s are filled with the long branching haus- 

 toria from the hjjpha m, m. X 390.— After De Bary. 



Fig. 175.— Coniaia-bearing hyphse of Penmoapora infestans. a, formation of the 

 first conidia upon the ends of Blender pedicels ; b, the formation of the second and 

 third conidia ; the pedicel is proliferons from the base of each conidinm after It is 

 formed, and thus the conidia, which are actually terminal, come to appear lateral. 

 X SOO.— After De Bary. 



liarly formed lateral branches (haustoria), which thrust 

 themselves through their walls (Fig. 174, and Fig. 176, A, h). 

 The vegetative growth is entirely within the host, and also 



and a translation in " Grevillea," Vol. I., p. 117. See also Prings- 

 heim's " Jahrbucher fiir WissenachaftlicheBotanik," Vol. IX., p. 289, 

 and Max Cornu, in " Annales des Sciences Naturelles," 5e ser., tom. 

 XV. 



* See a description by W. G. Smith in " Grevillea," Vol. VI., 1878, 

 p. 1.53. 



