CYSTOPTERIS. 



[ 232 ] 



CYSTOSEtRA. 



CYSTOP'TERIS, Bernhardi. A genus 

 of Davalliese (Polypodiaceous Ferns), con- 

 Fig. 154. 



Cystopteris fragilis. 



A pinnule with the sori covered by the indusia. 



Magnified 10 diameters. 



taining several elegant little indigenous 

 species (fig. 154). 



BIBL. Hooker and Baker, Syn.Jil. 103. 



CYS'TOPUS,Le'veille'. A genus of Ure- 

 dinei (Phy corny cetous Fungi), of which the 

 4 white rust ' common on cabbages and other 

 Cruciferous plants is a good example ; ap- 

 pearing in white pustules, eventually burst- 

 ing and destroying the epidermis of the 

 leaves, stalks, flowers, and seed-vessels of 

 the infected plants. When fine slices of 

 these pustules are examined under the mi- 

 croscope, the mycelium is found, creeping 

 among the cells of the parenchyma, com- 

 posed of inarticulate, tubular, branched 

 filaments, with a colourless membrane and 

 whitish granular contents. Numerous rami- 

 fications spread out in the plane of the 

 epidermis ; while others spring up in tufts 

 of two to seven, or rarely singly, perpendi- 

 cular to the former, to produce spores. 

 These erect branches are at first merer, 

 pouches projecting from the horizontal fila- 

 ments; they gradually swell into ovate- 

 cylindrical or club-shaped sacs. The con- 

 tents in the summit of each such sac be- 

 come organized into a spore, which at length 

 quite fills up the top of the sac (sporange). 

 Then the sac or sporange becomes con- 

 stricted under this first spore, and the for- 

 mation of a second commences under the 

 constriction. This is repeated until a neck- 

 lace-like chain of spores is produced, the 

 spores subsequently becoming somewhat 

 cylindrical or cubical. The number appears 

 indefinite ; five and seven spores have Deen 

 found in a chain ; they are united by the 

 constricted portions of the sporange ; and 



even when they have fallen apart, these 

 connecting pieces are seen projecting on 

 them like parts of a stalk from which they 

 have been broken off. Both the adherent 

 sporangial membrane and the smooth proper 

 coat of the spores are colourless, the con- 

 tents granular and whitish. Tulasne has 

 recently discovered another form of spore, 

 spheroidal or trigonal, and of a yellow co- 

 lour, only one or two of which are formed 

 from the end of a fertile filament. Oospores 

 are also found deeply seated amongst the 

 mycelium ; and zoospores (PI. 27. fig. 14) 

 have been found by De Bary in C. can- 

 didus. See UBEDINEI. British species; 

 formerly placed in the Uredinei, but more 

 nearly allied to Peronosporce : 



C. candidus. LeV. Very common on 

 Cruciferae, producing great distortion in the 

 growth. (Jredo Candida, Pers., Grev. Sc. 

 Crypt. Fl. t. 251. 



C. cubicus, Str. On goatsbeard. Cooke, 

 Exs. no. 88. 



C.Sepigoni,T)Q By. On Spergularia rubra. 

 Cooke, Exs. no. 88. 



C.spinulosus, De By. On Cirsium arvense. 

 Cooke, Exs. no. 89. 



BIBL. Le'veille', Ann. Sc. Nat. 3 s^r. 

 viii. 369 ; Berkeley, Hart. Trans, iii. 265 

 (figs.); De Bary, Brandpilze,^ei\m, 1853, 

 p. 20, pi. 2. figs. 3-7, and Ann. Sc. Nat. 

 1803, xx. 130 (zoospores) ; Tulasne, Ann. 

 Sc. Nat. 4 s$r. ii. 108, 171 ; Sachs, Bot. 

 279. 



C YSTOSEI'RA, Ag. A genus of Fuca- 

 ceee(Fucoid Algae), of much-branched habit, 

 some species of which are common on rocks 

 in tide-pools or between tide-marks. The 

 gradually attenuated branches contain in- 

 flated air-sacs, at intervalsalong their length, 

 within their substance. The conceptacles 

 are immersed in the ends of the branches, 

 which are pierced by their numerous pores. 

 They contain both spores and antheridia, 

 but not mixed ; the spores occur at the bot- 

 tom of the cavity, the antheridia above, near 

 the pore. The antheridia have only a single 

 coat. The antherozoids are expelled in a 

 mass, and soon after begin to move, turning 

 rapidly unon their axes. They are oval or 

 spnerical in one direction, and rather com- 

 pressed in the other. They have two cilia 

 inserted on a red granule ; the long cilium 

 in front moves rapidly, while the posterior 

 short one is motionless. See FUCACEJE. 



BIBL. Harvey, Mar. Alg. pi. 1 B ; Phyc. 

 Brit. 133, &c. ; Thuret, Ann. Sc. Nat. 3 se"r. 

 xvi. pp. 7 & 10. 



