ENCHONDROMA. 



[ 283 ] 



ENDOSMOSE, 



E. farcimen. Smaller than the last, 

 1-14;V2"; intornally whitish. 



E. arcuatit, (,'1. 



Two other species. 



Diijardiu's genus Enchehjs belongs to Cy- 

 clidium. 



BiBL. Ehrenb. Inf. 298 ; Dujanlin, Inf. 

 385; Stein, Inf. 137; Clap. & La:hm,/«y. 

 309 : Kent, Inf. o09. 



ENCHONDRO'MA. See Tumours. 



EXC YONE'MA,Kutz.— A genus of Dia- 

 tomaceiB. 



Char. Frustules resembling those of Cym- 

 bella, arranged mostly in longitudinal series, 

 in gelatinous tubes; freshwater. 



Valves very variable in form, even in the 

 same tube, showing how httle dependence 

 is to be placed upon this feature as a cha- 



E. prostratum (PI. 19. fig. 10). Fila- 

 ments nearly simple; length of frustules 

 1-1560 to 1-600". 



E. cfpspitositm. Filaments divided at the 

 ends, tufted. 



2 other European species, and 2 foreign. 



BiBL. KiitzLng, BacUl. 82, and Sp. Alq. 

 61; Ralfs, Ann. X. II. 1845, xvi. Ill; 

 Berkeley, ib. 1811, vii. 449 ; Smith, Brit. 

 Diat. ii.'68; liabenhorst, Fl. AUj. i. 85. 



ENDIC'TYA, Ehr.=CosciNODiscus in 

 part. E. oceanica=C. or. K. 



ENDOCARTOX, Hedw^— A genus of 

 Lichens, tribe Pyrenocarpei, with pale peri- 

 thecia immersed in a peltale or squamiform 

 coriaceous thallus ; gi-owing on rocks, in 

 streams, and on the ground. 



4 British species : E. miniatum,Jluviatile, 

 rufescens, and hepaticu'rn. 



BiBL. Leighton, Angioc. Lich., Ecn/ Soc. 

 1851, 10, pi. 1, and Lidi. Fl. 441 ; Tulasne, 

 Ann. Sc. Nat. 3 ser. xvii. 90, 218, ])ls. 10 & 

 12; Hook. Br. Fl. ii. pt. 1. 159; Schajrer, 

 Enum. 230, pi. 9. fig. 2. 



EX'DOCHROME.— This term is applied 

 to the cell-contents, or the miscellaneous 

 collection of substances and structures en- 

 closed in the cavity of a cell. In an Alga, 

 therefore, like Zygnema, it comprehends 

 the pritnordial utricle or layer of protoplasm 

 lining the cell-wall, together with the 

 chlorophyll-globules or vesicles, starch - 

 grauides, nucleus, and liquid and granular 

 protoplasm contained in the cavity of the 

 cell. It is perhaps a useful word in rouglily 

 describing a species, but it is too indefinite 

 to be admissible in any accurate description 

 of cellular structures ; moreover, as it is 

 not a definite collection of substances, nor 



always coloured, the use of the term cell- 

 contents is to be preferred in all cases, as 

 not indicating any positive characters. 



EXDOCOCCUS, Nyl.— A genus of Li- 

 chens containing the parasitic species of 

 Verrucaria. 



BiBL. Leighton, Lich. Fl. 492. 



EXDODRO'MIA, Berk. A curious ge- 

 nus of Mucorini (Phycomycetous Fungi), 

 distinguished by a very delicate vesicle per- 

 forated by the stem, filled with delicate 

 branched radiating threads and globose 

 spores, each of which has a nucleus en- 

 dowed with active motion. E. vitrea, the 

 only species, is found on sticks in damp 

 woods. 



BiBL. HooTc. Jn. iii. 79 ; Berk. Outl. 408. 



EX'DOCtEN. See Monocotyledons. 



EXUO'GONE, Lk.— A genus of Muco- 

 rini (Phycomycetous Fungi), consisting of 

 one or two Ilypogaeous species, the flocci 

 being collected into a globose spongy mass, 

 and terminated by globose vesicles, solitary 

 or in fascicles. Two species, E. pisiformisj 

 Lk., and E. lactijlua, B. & Br., have been 

 found in this country. 



BiBL. Atm. N. H. 1846, xviii. 81 ; Berk. 

 Ouil. 409. 



ENDOS'MOSE, Osmosis or Dialysis.— 

 This name is applied to a phenomenon 

 which takes place when two difl'erent li- 

 quids, having an attraction for each other, 

 are separated merely by a porous diaphrag-m 

 or an organic membrane. A diffusion takes 

 place, by which the liquids become mixed, 

 but one of them flows more rapidly into 

 the other. Thus when alcohol and Vater 

 are so placed, the water flows into the 

 alcohol (endosmose) much more strongly 

 than the alcohol into the water (exosmose). 

 The same attraction occurs when syrup or 

 a solution of gum is substituted "for the 

 spirit, and also alkaline salts. When acids 

 or acid salts are placed in the same relation 

 to water, the current is strongest towards 

 the water. Acids and alkaline solutions 

 exert the strongest action, neutral sub- 

 stances the weakest. Dilute solutions act 

 more efficiently (proportionally) than strong 

 ones. The importance of the effects of 

 endosmose on microscopic objects viewed in 

 liquids, has been mentioned in the Introd. 

 (p. xli). Delicate structures are often ad- 

 vantageously wetted with dilute solution 

 of sugar, common salt, or glycerine, to 

 prevent the changes from endosmosis which 

 result from the u.-e of pure water. 



Graham divided organic matters into two 



