SEA- WATER AQUARIA. 123 



ject from Lloyd's Handbook to the Marine Aquarium oj the Crystal 

 Palace (1872). It runs thus : — 



" Mrs. Thynne need not have sent from London to the sea 

 for sea-weeds to revivify the water for her flagging corals, even 

 though she for the first time thus intelligently applied the purpose 

 of the vegetation in a marine aquarium ; as had she but exposed 

 the water long enough to light, sea-weeds would inevitably have 

 come, even in London, without their having been visibly put in — 

 and they doubtlessly did come without being recognised, in her 

 case. It was the same with Mr. Gosse, and with every other 

 writer who recommended the putting masses of grown-uj) or even 

 young plants into tanks* Such vegetation is very elegant, often 

 as much so, and as interesting, as the animals themselves, but 

 with the exception of the knowledge taught by Warington and 

 Gosse, namely, that a few of the red Algce can be grown in cap- 

 tivity in darkness or in much shade, or by the interposition of 

 coloured media, it is not known how to systematically cultivate 

 the green kinds, as Ulva^ Porphyra^ and Enteromorpha^ or indeed 

 hardly any others, whether they be brown, or red, or green. By 

 chance, indeed, sometimes one here and there (and even difficult 

 kinds occasionally, as Delesseria, Lafninaria, and others) may be 

 grown more or less well ; but as the reason is unknown, a repeti- 

 tion of success can seldom be had ; and, in fact, so uncertain are 

 these Algce^ and so easily are they killed from a slight disturbance 

 of condition, that sometimes an alteration of position of even the 

 extent of a few inches in a tank, without the attachment or any 

 other part being disturbed or injured, will cause a growing plant 

 to die. It may be that some AlgcB need the alternate exposure 

 and submersion of tides, or the successive periods of rest and 

 growth afforded by the cold and warmth of actual nature ; or 

 possibly some require tidal actions, or the influence of the rain 

 they occasionally get when the tide is out. Be that as it may, it 

 is certain that with our present knowledge, the putting into an 

 aquarium of masses of already grown sea-weed, especially the 

 green kinds, whether they be young or old, or attached to stones 

 or not, or of any ready-grown fresh-water plant, is not only very 

 seldom attended with an after successful result, but so much 

 positive harm is done by the decomposition arising from their 



