glaucus- 第23部分

will　do；　but　a　better　defence　is　a　plate　of　glass；　raised　on　wire　

some　half…inch　above　the　edge；　so　as　to　admit　the　air。　　I　am　not　

sure　that　a　sheet　of　brown　paper　laid　over　the　vase　is　not　the　best　

of　all；　because　that；　by　its　shade；　also　guards　against　the　next　

evil；　which　is　heat。　　Against　that　you　must　guard　by　putting　a　

curtain　of　muslin　or　oiled　paper　between　the　vase　and　the　sun；　if　

it　be　very　fierce；　or　simply　（for　simple　expedients　are　best）　by　

laying　a　handkerchief　over　it　till　the　heat　is　past。　　But　if　you　

leave　your　vase　in　a　sunny　window　long　enough　to　let　the　water　get　

tepid；　all　is　over　with　your　pets。　　Half　an　hour's　boiling　may　

frustrate　the　care　of　weeks。　　And　yet；　on　the　other　hand；　light　you　

must　have；　and　you　can　hardly　have　too　much。　　Some　animals　

certainly　prefer　shade；　and　hide　in　the　darkest　crannies；　and　for　

them；　if　your　aquarium　is　large　enough；　you　must　provide　shade；　by　

arranging　the　bits　of　stone　into　piles　and　caverns。　　But　without　

light；　your　sea…weeds　will　neither　thrive　nor　keep　the　water　sweet。　　

With　plenty　of　light　you　will　see；　to　quote　Mr。　Gosse　once　more；　

（33）　〃thousands　of　tiny　globules　forming　on　every　plant；　and　even　

all　over　the　stones；　where　the　infant　vegetation　is　beginning　to　

grow；　and　these　globules　presently　rise　in　rapid　succession　to　the　

surface　all　over　the　vessel；　and　this　process　goes　on　

uninterruptedly　as　long　as　the　rays　of　the　sun　are　uninterrupted。



〃Now　these　globules　consist　of　PURE　OXYGEN；　given　out　by　the　plants　

under　the　stimulus　of　light；　and　to　this　oxygen　the　animals　in　the　

tank　owe　their　life。　　The　difference　between　the　profusion　of　

oxygen…bubbles　produced　on　a　sunny　day；　and　the　paucity　of　those　

seen　on　a　dark　cloudy　day；　or　in　a　northern　aspect；　is　very　

marked。〃　　Choose；　therefore；　a　south　or　east　window；　but　draw　down　

the　blind；　or　throw　a　handkerchief　over　all　if　the　heat　become　

fierce。　　The　water　should　always　feel　cold　to　your　hand；　let　the　

temperature　outside　be　what　it　may。



Next；　you　must　make　up　for　evaporation　by　FRESH　water　（a　very　

little　will　suffice）；　as　often　as　in　summer　you　find　the　water　in　

your　vase　sink　below　its　original　level；　and　prevent　the　water　from　

getting　too　salt。　　For　the　salts；　remember；　do　not　evaporate　with　

the　water；　and　if　you　left　the　vase　in　the　sun　for　a　few　weeks；　it　

would　become　a　mere　brine…pan。



But　how　will　you　move　your　treasures　up　to　town？



The　simplest　plan　which　I　have　found　successful　is　an　earthen　jar。　　

You　may　buy　them　with　a　cover　which　screws　on　with　two　iron　clasps。　　

If　you　do　not　find　such；　a　piece　of　oilskin　tied　over　the　mouth　is　

enough。　　But　do　not　fill　the　jar　full　of　water；　leave　about　a　

quarter　of　the　contents　in　empty　air；　which　the　water　may　absorb；　

and　so　keep　itself　fresh。　　And　any　pieces　of　stone；　or　oysters；　

which　you　send　up；　hang　by　a　string　from　the　mouth；　that　they　may　

not　hurt　tender　animals　by　rolling　about　the　bottom。　　With　these　

simple　precautions；　anything　which　you　are　likely　to　find　will　well　

endure　forty…eight　hours　of　travel。



What　if　the　water　fails；　after　all？



Then　Mr。　Gosse's　artificial　sea…water　will　form　a　perfect　

substitute。　　You　may　buy　the　requisite　salts　（for　there　are　more　

salts　than　〃salt〃　in　sea…water）　from　any　chemist　to　whom　Mr。　Gosse　

has　entrusted　his　discovery；　and；　according　to　his　directions；　make　

sea…water　for　yourself



One　more　hint　before　we　part。　　If；　after　all；　you　are　not　going　

down　to　the　sea…side　this　year；　and　have　no　opportunities　of　

testing　〃the　wonders　of　the　shore；〃　you　may　still　study　Natural　

History　in　your　own　drawing…room；　by　looking　a　little　into　〃the　

wonders　of　the　pond。〃



I　am　not　jesting；　a　fresh…water　aquarium；　though　by　no　means　as　

beautiful　as　a　salt…water　one；　is　even　more　easily　established。　　A　

glass　jar；　floored　with　two　or　three　inches　of　pond…mud　（which　

should　be　covered　with　fine　gravel　to　prevent　the　mud　washing　up）；　

a　specimen　of　each　of　two　water…plants　which　you　may　buy　now　at　any　

good　shop　in　Covent　Garden；　Vallisneria　spiralis　（which　is　said　to　

give　to　the　Canvas…backed　duck　of　America　its　peculiar　richness　of　

flavour）；　and　Anacharis　alsinastrum；　that　magical　weed　which；　

lately　introduced　from　Canada　among　timber；　has　multiplied；　self…

sown；　to　so　prodigious　an　extent；　that　it　bid　fair；　a　few　years　

since；　to　choke　the　navigation　not　only　of　our　canals　and　fen…

rivers；　but　of　the　Thames　itself：　　（34）　or；　in　default　of　these；　

some　of　the　more　delicate　pond…weeds；　such　as　Callitriche；　

Potamogeton　pusillum；　and；　best　of　all；　perhaps；　the　beautiful　

Water…Milfoil　（Myriophyllium）；　whose　comb…like　leaves　are　the　

haunts　of　numberless　rare　and　curious　animalcules：…　these　（in　

themselves；　from　the　transparency　of　their　circulation；　interesting　

microscopic　objects）　for　oxygen…breeding　vegetables；　and　for　

animals；　the　pickings　of　any　pond；　a　minnow　or　two；　an　eft；　a　few　

of　the　delicate　pond…snails　（unless　they　devour　your　plants　too　

rapidly）：　　water…beetles；　of　activity　inconceivable；　and　that　

wondrous　bug　the　Notonecta；　who　lies　on　his　back　all　day；　rowing　

about　his　boat…shaped　body；　with　one　long　pair　of　oars；　in　search　

of　animalcules；　and　the　moment　the　lights　are　out；　turns　head　over　

heels；　rights　himself；　and　opening　a　pair　of　handsome　wings；　starts　

to　fly　about　the　dark　room　in　company　with　his　friend　the　water…

beetle；　and　（I　suspect）　catch　flies；　and　then　slips　back　demurely　

into　the　water　with　the　first　streak　of　dawn。　　But　perhaps　the　most　

interesting　of　all　the　tribes　of　the　Naiads；　…　（in　default；　of　

course；　of　those　semi…human　nymphs　with　which　our　Teutonic　

forefathers；　like　the　Greeks；　peopled　each　〃sacred　fountain；〃）　…　

are　the　little　〃water…crickets；〃　which　may　be　found　running　under　

the　pebbles；　or　burrowing　in　little　galleries　in　the　banks：　　and　

those　〃caddises；〃　which　crawl　on　the　bottom　in　the　stiller　waters；　

enclosed；　all　save　the　head　and　legs；　in　a　tube　of　sand　or　pebbles；　

shells　or　sticks；　green　or　dead　weeds；　often　arranged　with　quaint　

symmetry；　or　of　very　graceful　shape。　　Their　aspect　in　this　state　

may　be　somewhat　uninviting；　but　they　compensate　for　their　youthful　

ugliness　by　the　strangeness　of　their　transformations；　and　often　by　

the　delicate　beauty　of　the　perfect　insects；　as　the　〃caddises；〃　

rising　to　the　surface；　become　flying　Phryganeae　（caperers　and　sand…

flies）；　generally　of　various　shades　of　fawn…colour；　and　the　water…

crickets　（though　an　unscientific　eye　may　be　able　to　discern　but　

little　difference　in　them　in　the　〃larva；〃　or　imperfect　state）　

change　into　flies　of　the　most　various　shapes；　…　one；　perhaps；　into　

the　great　sluggish　olive　〃Stone…fly〃　（Perla　bicaudata）；　another　

into　the　delicate　lemon…coloured　〃Yellow　Sally〃　（Chrysoperla　

viridis）；　another　into　the　dark　chocolate　〃Alder〃　（Sialis　lutaria）：　　

and　the　majority　into　duns　and　drakes　（Ephemerae）；　whose　grace　of　

form；　and　delicacy　of　colour；　give　them　a　right　to　rank　among　the　

most　exquisite　of　God's　creations；　from　the　tiny　〃Spinners〃　（Ba塼is　

or　Chloron）　of　incandescent　glass；　with　gorgeous　rainbow…coloured　

eyes；　to　the　great　Green　Drake　（Ephemera　vulgata）；　known　to　all　

fishermen　as　the　prince　of　trout…flies。　　These　animals；　their　

habits；　their　miraculous　transformations；　might　give　many　an　hour's　

quiet　amusement　to　an　invalid；　laid　on　a　sofa；　or　imprisoned　in　a　

sick…room；　and　debarred　from　reading；　unless　by　some　such　means；　

any　page　of　that　great　green　book　outside；　whose　pen　is　the　finger　

of　God；　whose　covers　are　the　fire　kingdoms　and　the　star　kingdoms；　

and　its　leaves　the　heather…bells；　and　the　polypes　of　the　sea；　and　

the　gnats　above　the　summer　stream。



I　said　just　now；　that　happy　was　the　sportsman　who　was　also　a　

naturalist。　　And；　having　once　mentioned　these　curious　water…flies；　

I　cannot　help　going　a　little　farther；　and　saying；　that　lucky　is　the　

fisherman　who　is　also　a　naturalist。　　A　fair　scientific　knowledge　of　

the　flies　which　he　imitates；　and　of　their　habits；　would　often　

ensure　him　sport；　while　other　men　are　going　home　with　empty　creels。　　

One　would　have　fancied　this　a　self…evident　fact；　yet　I　have　never　

found　any　sound　knowledge　of　the　natural　water…flies　which　haunt　a　

given　stream；　except　among　cunning　old　fishermen　of　the　lower　

class；　who　get　their　living　by　the　gentle　art；　and　bring　to　indoors　

baskets　of　trout　killed　on　flies；　which　look　as　if　they　had　been　

tied　with　a　pair　of　tongs；　so　rough　and　ungainly　are　they；　but　

which；　nevertheless；　kill；　simply　because　they　are　（in　COLOUR；　

which　is　all　that　fish　really　care　for）　exact　likenesses　of　some　

obscure　local　species；　which　happen　to　be　on　the　water　at　the　time。　　

Among　gentlemen…fishermen；　on　the　other　hand；　so　deep　is　the　

ignorance　of　the　natural　fly；　that　I　have　known　good　sportsmen　

still　under　the　delusion　that　the　great　green　May…fly　comes　out　of　

a　caddis…bait；　the　gentlemen　having　never　seen；　much　less　fished　

with；　that　most　deadly　bait　the　〃Water…cricket；〃　or　free　creeping　

larva　of　the　May…fly；　which　may　be　found　in　May　under　the　river…

banks。　　The　consequence　of　this　ignorance　is　that　they　depend　for　

good　patterns　of　flies　on　mere　chance　and　experiment；　and　that　the　

shop　patterns；　originally　excellent；　deteriorate　continually；　till　

little　or　no　likeness　to　their　living　prototype　remains；　being　tied　

by　town　girls；　who　have　no　more　understanding　of　what　the　feathers　

and　mohair　in　their　hands　represent　than　they　have　of　what　the　

National　Debt　represents。　　Hence　follows　many　a　failure　at　the　

stream…side；　because　the　〃Caperer；〃　or　〃Dun；〃　or　〃Yellow　Sally；〃　

which　is　produced　from　the　fly…book；　though；　possibly；　like　the　

brood　which　came　out　three　years　since　on　some　stream　a　hundred　

miles　away；　is　quite　unlike　the　brood　which　is　out　to…day　on　one's　

own　river。　　For　not　only　do　most　of　these　flies　vary　in　colo