EELS. 



[ 276 ] 



EL^EAGNACE^E. 



EELS, in vinegar (ANGUILLULAACETI). 

 EGGS. The minute ova of certain ani- 

 mals have always been favourite microscopic 

 objects on account of their curious forms, the 

 beautiful structure of their outer chitinous 

 envelope, their varied colours, and the sin- 

 gular lids with which some of them are 

 furnished. The most interesting are those 

 of insects : among them we may mention 

 the brown eggs of the puss-moth, Cerura 

 vinula (PI. 39. fig. 19) j of the large and 

 small cabbage-butterflies, Pontia brassicce 

 and rapes (PI. 39. fig. 21) ; of the small 

 tortoiseshell butterfly, Vanessa urticce ; the 

 angle-shades moth, Noctua or Phlogophora 

 meticulosa ; the common meadow brown 

 butterfly, Hipparchia Janira ; the brimstone 

 moth, Rumia cratcegata ; the water-scorpion, 

 Nepa ranatra ; the common cow-dung-fly, 

 Scatophaga stercoraria, which are very 

 common on cow-dung ; the bug, Cimex 

 lectularius (PI. 39. fig. 20), Hydrometra 

 stagnorum, &c. 



Their surfaces exhibit markings of the 

 most varied forms spines, tubercles, pits or 

 processes, sometimes of considerable length 

 (PL 21. figs. 22, 23), often arranged with 

 great symmetry, and frequently closely re- 

 sembling the cellular structure of plants in 

 appearance. Sometimes very delicate an- 

 gular spaces are mapped out upon them, the 

 intervals being most minutely dotted, as in 

 the eggs of the common blow-fly, Musca 

 vomitoria (PI. 34. fig. 35). 



It is a genera] fact, exemplified in both 

 the animal and vegetable kingdom, that 

 unicellular, or the corresponding stages or 

 phases of the higher organisms, exhibit 

 markings of some kind upon their external 

 membrane or wall, as is seen in the cells 

 of the Desmidiaceae, the Diatomacese, the 

 eggs of animals, the spores and pollen-grains, 

 and the seeds of plants. 



At certain seasons of the year, the eggs 

 of some aquatic animals are provided with 

 a very thick horny coat, as in the Entomos- 

 traca, Hydra, &c. These have been called 

 winter ova, from the notion that here was 

 a defence against a low temperature ; they 

 correspond to the resting-spores or resting- 

 stages of the Infusoria and Algae, some of 

 which were formerly included in the ani- 

 mal kingdom. The formation of this coat 

 can scarcely have any relation to tempera- 

 ture, either from its structure or from its 

 requirement in an organism which has no 

 heat to retain. Its presence would be per- 

 fectly intelligible, however, as a means of 



protection from evaporation when the 

 pools become dry j and for this purpose its 

 structure is well adapted. It might also 

 afford ^a protection against the attacks of 

 predatory animals, many of which could 

 easily devour an ovarian ovum, while they 

 could not break through the horny cases of 

 the winter ova ; and these winter ova are 

 only formed when the ova are not to be 

 hatched soon after extrusion from the pa- 

 rent. The ova of those animals which are 

 never hatched immediately after leaving 

 the parent, have always a coat correspond- 

 ing to that of the winter ova. 



The structure and development of eggs 

 are considered under OVUM; see also SHELL. 

 BIBL. See OVUM. 



EHRENBERGI'NA, Reuss. A Cassi- 

 duline Foraminifer with the later portion 

 of the shell uncoiled. 



BIBL. Carpenter, Introd. Foram. 198. 

 ELACHISTEA, Fries. A genus of 

 Myrionemaceae (Fucoid Algae). Minute 

 epiphytic sea-weeds, consisting of a dense 

 tuft of simple, articulated, olivaceous fila- 

 ments, from a common tubercular base 

 composed of a closely combined mass of 

 dichotomously branched filaments, growing 

 upon larger Fucoids, such as Fucus, Hi- 

 manthalia, Cystoseira, &c. The fructifica- 

 tion is borne in two forms unilocular 

 (spores, Harvey) and multilocular sporanges 

 (paranemata, Harvey). The unilocular are 

 formed of metamorphosed terminal cells at 

 the ends of the dichotomous filaments; they 

 are long ovoid sacs, the contents of which 

 are ultimately converted into a vast number 

 of zoospores. The multilocular sporanges 

 arise exactly in the same place and way, 

 but take the form of long, slender, articu- 

 lated filaments, in the joints of which simi- 

 lar but smaller zoospores are developed. 

 Both forms of fructification nestle on the 

 surface of the tubercle of the frond, at the 

 base of the long simple filaments. The 

 zoospores of both kinds of fruit germinate ; 

 and these occur together in some cases (E. 

 attenuata], in others at different seasons of 

 the year. Harvey describes seven British 

 species ; the tufts of some are half an inch 

 long, of others less than a line, 



BIBL. Harvey, Mar. Alg. 49, pi. 10 F ; 

 Pkyc. Brit. pis. 240, 260, 261, &c. ; Dillw. 

 Conferv. pi. 66 &c. ; Thuret, Ann. Sc. Nat. 

 3 s5r. xiv. p. 236, pi. 25. figs. 1-4. 



EL JEAGNA'CEJE. A family of Dico- 

 tyledons, the leaves of which are usually 

 covered with a kind of scurf formed of very 



