PAKASITES. 



[ -"'J ] 



PAILMKLIA. 



which is the 3Iuscardine of tlio Silk-wurm, 

 BoTRYTis ba^siaiia, which soiUL'limcs occii- 

 sions euoruious loss to the silk-cidtivators. 

 This fungus grows in or upon auy part of 

 the silk-worm, Bombi/.v mori, iu its larva, 

 chrysaHs, aud imago forms. It is not fully 

 developed until after the death of the insect ; 

 but if the spores penetrate the body of a 

 living specimen and this is placed iu a damp 

 and contined atmosphere, the germination 

 takes place, aud a development of the fungus 

 ensues, which destroys the tissues and organs, 

 finally causing death. It has been developed 

 on many other Lepidoptera which have 

 been inoculated with it ; and even the larva) 

 of certain Coleoptera take it. It is very 

 common to hud flies iu autumu infested 

 with a f migus, a kind of muscardine of tiies : 

 this belongs to the genus Spohendonema ; 

 its mycehal filaments ramify in the interior 

 of the body, and emerge at the articulations 

 of the segments of the abdomen to bear fruit, 

 killing the fly. A number of so-called genera 

 of Fungi and Alg8e have been described by 

 Eobin and Leidy as occurring in the intes- 

 tines &c. of insects : these appear to us to 

 be imperfect organisms (see Enterobryus, 

 Aethrojxitus, Leptothrix, Cladophy- 

 titm). Several species of Cordyceps infest 

 the larvae of insects, the mycelium destroy- 

 ing them aud gradually completely dis- 

 placing the internal organs, while the skin 

 retains its shape and dries ; the fruit sub- 

 sequently breaks out from the anterior or 

 posterior extremity (see Sph^ria). Some 

 species of Isaria, described as parasites, 

 gro\\- upon dead insects ; but these are mere 

 conditions of different species of Cordyceps. 



The microscopic vegetahle parasites of 

 Plants 



are very numerous, all belonging to the class 

 of Fimgi. Much confusion exists in many 

 works between the true parasites and mere 

 epiphytes ; and it is sometimes very difficult 

 to draw any line of demarcation. Among 

 the undoubted parasites are all the genera 

 and species of the family Uredinei, together 

 with a large portion of the other genera of 

 Coniomycetes and the Ascomycetous forms 

 to which they mostly belong. Among the 

 Hyphomycetes may especially be cited the 

 genus Peroxospora, P. infestamheiug the 

 potato-fimgus. Fusisporium, Oidium, &c. 

 form desti'uctive mildews ; and among the ' 

 Ascomycetes, the Erysiph^, and espe- 

 cially their mycelia (commonly forming- 

 spurious Oidid), ar^' v>ell-kiio\vn pests. ( 



Further particulars are given under Potato- 

 FifNGUS {Butrytis infestam) ,\ i^k-Fxjsgvh, 

 and Bligut. The organisms described as 

 Unicellular Alga3, under the names of 

 Chytridium and Pythium, are parasitic 

 on Confer voids. 



BiBL. Robin, Vcyet. Parasit. ; Bseren- 

 sprung, Ann. N. II. xii. ; Siebold, Wayner\s 

 Hand. d. Pliys.-, Hdunoyev, MuUer''s Arc/t. 

 1842 ; Beimett, Bd. Phil. Tr. xv. ; Archer, 

 Qu. Mic. Jii. 1872, 366 ; Cobbold, Parasites ; 

 Leuckart, Mensch. Parasit. 18S1 ; Murio, 

 Mn. M. Jn. vii. 149 ; .^laddox, Mic. Tr. 1866 ; 

 Beneden, Schmarotzer,\S7Q; Hallier, P%^o- 

 pathol. 1868 ; Kaltenbach, Pflanzcnfeinde 

 (Insects), 1872 ; Giebel, Epizoa {Insects), 

 1874; Bounon, Par. diar. Cochin- China; 

 Gurlt, ^4rc/<. Nataryesch. 1878, 162 j ITartig, 

 PJlanzenKr. (Funyi), 1S80; Frank, AVawM. 

 P/l. {Funyi), 1880 ; Heller, Schmarotzer, 

 1880 ; Megnin, Paras. 1880 ; Ormerod, In- 

 jurious Insects, 1881 ; Cuhn, Paras. Alyce, 

 Beitrage, i. 87 ; Kiichenmeister, Parasiten, 

 1881 ; Bollinger, Pilzhranhh. nied. und 

 hah. Thiere, Bot. Centralblatt, ii. 274 (Jn. 

 Mic. Soc. 1881, 492) ; Halher, Zeitschr. 

 Paras. Kunde. 



PAPtEN'CHYMA. See Tissues, Vege- 

 table. 



PARKE' RI A, Carpenter. — A large 

 spheroidal Arenaceous Foraminifer, attain- 

 ing 3 inches and more in diameter, and 

 consisting of a chambered conical centi'e- 

 piece (primordial chamber-cone) surrounded 

 by numerous concentric lamellae and their 

 interspaces, traversed aiid connected by 

 radial tubes, all of cauueilated (labyrinthic) 

 structure. Fossil in the Greensand. 



BiBL, Carpenter, Phil. Trans. 1869, 721. 



PARKE'RIA, Hooker, = Cerato- 



PTERIS. 



PAR^IE'LIA, Acli. — An extensive genus 

 of Parmeliacese, characterized by the spread- 

 ing, lobed, foUaceous thallus, with orbi- 

 cular apothecia fixed by a central point 

 beneath ; spores simple ; growing upon 

 trees, palings, rocks, stones, walls, &c. 

 The species with bilocular spores form the 

 genus Physcia. P. parietina, the yellow 

 wall-Uchen, is one of the commonest plants 

 of this family, and furnishes a ready means 

 of observing the structm-e both of the 

 apothecia and the 'spermogonia (PL 37. 

 figs. 1-3). 



BiBL. Hook. Br. Fl. ii. pt. 1. 202; Engl. 

 Bot. pi. 194 ; Schaerer, Enum. Lich. Europ. ; 

 Tulasne, Ann. Sc. Nat. 3. xvii. 66, 137 : 

 Leighton, Lich, Flora, 114. 



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