tECIDIUM. 



[ 19 ] 



AElilAL ROOTS. 



■wliicli is ultimately only recognizable where 

 it coimeets the spores together iu a monili- 

 foriu series. Tiie spores iu most cases now 

 acquire a deeper colour (except in ^. leuco- 



^cidium Compositarum, Mart. 

 Fio-. 6. 



Peridia in various stages of growth on the surface of ; 

 leaf: 30 diam. 



Fig. 6 a. 



Perpendicular section through a hurst peridium, show- 

 ing the sporanges contained in it : 100 diam. 



coniuni), owing to contents chieiiy accu- 

 mulated in the centre. Their membrane 

 is colom-less, their form finally irregularly 

 polygonal ; and the diameter varies much, 

 even in ripe spores of one and the same 

 species, from 1-1000 to 1-1800 of an inch. 

 The upper spores are often ripe at an epoch 

 when young spores are .-till in course of pro- 

 duction at the lower end of the sporanges ; 

 finally, however, the development ceases be- 

 low, and the tube elongates a little beneath 

 the lowest spore, forming a kind of pedicle 

 or basicUum to the row. The ripe spores 

 either soon fall apart and fill the cup as a 

 loose powder, along with short incomplete 

 sporanges, or the rows persist even after 

 they are mature, held together probably by 

 a firmer peridial membrane. 



The British species of ^Ecidium are nu- 

 merous; more than thirty are described by 

 Berkeley in the Jiritish Flora, many df 

 which are common, especially those of the 

 Mints, the Compositte (such as the Colts- 

 foot, &.C.), the Barberr}', the Cloosebeny, 

 Buckthorn, Spurge, Nettle, &c. (^Z?. Coin- 

 pusitarum, Mcutlice, Berheridis, Grossularice, 

 crasstcm, Euphorbice, Urticce, 4'C-)- 



Oersted and De Bary have made expe- 

 riments which seem to prove that jEcidiKin 

 Berberidis is a development of Puccinia 

 (//•ainims ; a full account of which will 

 be found in Cooke and Berkeley, Futiyi, 

 p. ISO. 



BiBL. For Species : — Brit. Flora, ii. pt. 2. 

 p. 309 ; Greville, Sc. Crypt. Flora, pis. 7, 

 02, 97, 180, 209 ; Reess, Disp. Ured. 1S79. 



For Auat. and Physiol. : — Uuger, Exan- 

 theme, pp. 297, 300,' t. 3. f. 18, 19, t. 4; 

 Meyen, PJlanzenpath. pp. 143, 148-50 ; 

 Tulasne, Vompt. limdus, March 24 and 31, 

 1851 ; Ann. d. Sc. A'af. ser. 3. t. xv. ; ibid. 

 ser. 3. t. vii. p. 45; ser. 4. t. ii. pp. 126, 173; 

 Leveille, Sur le dev. des Uredinees, A7in. 

 des Sc. Nat. ser. 2. t. xi. ; Corda, Icon. Funy. 

 iii. t. 3. f. 45 ; De Bar}', Brandpilze, J3erliu, 

 1853, p. 55 et seq. pis. 5, G, and 7 ; Sachs, 

 BotaniJi, 1874, p. 332 ; Heufrev, Bot. (Mas- 

 ters), 1878, p. 460. 



^GERITA, Persoon.— A genus of Stil- 

 bacei (Plyphomycetous Fungi) characteiized 

 by short necklace-like threads consisting of 

 irregular spores produced from flexuous, 

 branched, radiatiug- sporophores, forming a 

 subglobose mass. yE. Candida, Persoon, 

 grows on damp twigs iu marshy places, 

 consisting of scattered white grains about 

 the size of a poppy-seed. ^E. setosa, Grev., 

 belongs to the genus Volutelhi. 



BiBL. Greviile, Crypt. Fl pi. 268. fig. 1 ; 

 Ann. N. H. 1859, iii. 362, jjl. ix. f. 7. 



^FIGYRIA. — A genus of Infusoria=^r- 

 vilia, Duj. JE. leyumen=Erv. leyumen, D. 

 Three other species. 



BiBL. Claparede and Lachmann, Infus. 

 &-C. i. p. 288. 



ANGSTR(E'MIA, Br. and Sch.— A ge- 

 nus of LeptotrichaceoLis Mosses, including 

 many Dicrana, and Ccrutodon cylindricus, 

 Br. and Sch. 



BiBL. Miiller, Sipiops. Muse. i. p. 426 ; 

 Wilson, Bryoloy. Brit. pp. 72, 85. 



AERIAL ROOTS.— A very large pro- 

 portion of the exotic Orchids are epiphytic 

 plants and produce aerial roots, which ab- 

 sorb moisture from the atmosphere; the 

 same structure occurs in many tropical 



c'2 . 



