ERIOSOMA. 



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ERYSIPHE. 



ERIOSO'MA. See Aphid^. 



ERIOSTORA, Berk. & Br.— A genus 

 of Sphajronemei (Stylosporous Fungi j, do- 

 scribed (E. leucosfoma) a,3 foiTuing minute 

 brown spots upon dead leaves of the bulrush. 

 The conceptacles are globose, and collected 

 in numbers on the stroma, bursting by a 

 single common (white-bordered) pore to 

 discharge the spores (stylospores), which 

 are filiform and very slender, and arise in 

 fours from a sporophore. (See Coniomy- 



CETES.) 



BiBL. Berk, and Br. Ann. N. H. 1850, 

 V. 455, pi. 11. fi^. 1. 



ERUPTIONS, CTTTANEOUS.— The scales, 

 crusts, scabs, contents of vesicles, pustules, 

 &c. formed in various diseases of the skin, 

 usually consist of epidermic cells alone, 

 more or less fiatteued or othei'wise altered, 

 or of these with the ordinary products of 

 inflammation. Granules of soot are fre- 

 quently found, in London at least, mixed 

 with the above elements ; and these were 

 once regarded as the microzymes of small- 

 pox. Fmigi exist in the crusts of some 

 skin-diseases, as FAvrs, &c. The itch- 

 insect, Sarcoptes, must not be forgotten, 

 nor Demopex. See Parasites. 



ERVIL'IA, Duj. {J^f/yHa,C\. k Laehm.). 

 — A genus of Infusoria, of the family 

 Ervilina. 



Char. See the family. Marine. 



E. ler/nvien = Enplotes monoxtyhis, E. 

 (PI. 30." fig. 52 ; h, side view). Body with 

 two ventral contractile vesicles ; length 

 1-650 to 1-420". 



3 other species. 



BiBL. Duj. Infus. 455 ; Clap. & Lachm. 

 Inf. 288. 



"ERVILI'NA, Duj. (Dysterina, CI. & 

 Lachm.). — A family of Infusoria. 



Chen'. Body oval, more or less depressed, 

 entirely or partly ciliated, with a tail-like 

 foot, usually also with a persistent mem- 

 branous carapace. 



Genera : 



Carapace present. 



Composed of two distinct valves Idiina. 



Composed of two united valves. 



Valves united behind and below only ... Dyfteria. 



Valves united all dovm the back F.rriUa. 



Carapace absent Hiuleyia. 



Dujardin questions whether Urocentrum, 

 E., does not belong to this family. 



BiBL. Duj. hifus. p. 454; Clap.& Lachm. 

 Infus. p. 278. 



"ERY'SIPIIE, Hedw. fil.— A genus of 

 P^n-enoniycetes (AscomycetoTis Fungi), 

 consisting of little mildews overgTowing the 



leaves of living plants, mostly Dicotyledons. 

 The mycelium is formed of slender ramified 

 filaments, which spread and form an en- 

 tangled web over the epidermis of the in- 

 fected plant, sending into the substance 

 sucker-like processes or hausteria, by which 

 nourishment is obtained from the juices of 

 the leaf. From the creeping mycelium arise 

 numerous upright short-jointed filaments, 

 the last one or more of the cells or joints 

 of which sweUs so as to render the erect 

 filament clavate or monihform. These ex- 

 panded cells become detached with the 

 greatest readiness, and, w^hen they fall upon 

 the supporting leaf, germinate and produce 

 new mycelium threads. In this state the 

 Erysiphce cannot be distinguished from the 

 genus Oidiiim; and as this state is succeeded 

 in most cases by the true conceptacle of 

 the genus En/siphe, the Oidia (such as 

 O. Tuckeri, the Vine-fungus), which grow 

 under the same circumstances, but do not 

 produce conceptacles, are regarded by most 

 authors as iwpevfectEn/siphcs. (See Oidium, 

 PL 26. figs. 12-14.) \Vhen the mycelium 

 of an Erysiphe is developed late in the year, 

 it seldom produces any thing but the ovate 

 cells {conidia); but if developed early in the 

 summer, the mycelium grows at certain 

 points into denser white ^atahes {receptacles, 

 Lev.), fi'om which arise the conceptacles, 

 which are fertilized by poUinodia, as in 

 Eiirotinm. These are small globular sacs, 

 composed of a double layer of cells ; from 

 the base of the outside of the sac arise a 

 number of radiating filaments, simple or 

 branched (appetidicles, Lev.), while in its 

 interior are developed one or many sacs, 

 (asci, sporanges, Lev.), in each of which 

 are produced mostly eight sporidia. In 

 addition to the above, a third form of fruit 

 occurs, in which the conidium becomes 

 transformed into a sac (pycniduuu) filled 

 with minute spores. Tulasne has figured 

 a second form, apparently of conidia, in 

 Phyllactinia gidfata. 



Leveilld, in an elaborate essay on this 

 genus, has subdivided it into six genera, 

 which may perhaps be better taken as sub- 

 genera, and may be distinguished in the 

 following manner : — 



Conceptacles with one asciis. 

 Appendicles dichotomously branched. . . Fodosphtpria. 

 „ floocose Sphoerotheca. 



Conceptacles with v\any asci. 



„ aciculate FhyVactinia. 



„ uncinate Vncinula. 



„ dichotomously branched... Microsphairia, 



„ floccose Erysiphe. 



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