Mr. R. Warington's Notes on Animals in small Aquaria. 371 



simple means and with very little trouble, we shall be enabled 

 to grow and preserve these elegant and beautiful plants in all 

 their varied hues, as well as many of the wondrous forms of ani- 

 mal life usually found associated with them, for any length of 

 time ; and thus a much enlarged field for observation will be 

 brought within the limits of our aquarium. 



In order to obtain this desideratum, a medium having a blue 

 or green tint has been had recourse to, and of such a nature as 

 merely to colour, soften or diffuse the light, without materially 

 diminishing its quantity. This was at first accomplished by the 

 employment of a thin film of paint of the desired shade, of a 

 thin silk gauze of a blue colour, by layers of tissue paper tinged 

 blue and green, sometimes oiled to render them more trans- 

 parent, at others the sheets of paper being supeqiosed until the 

 desired effect was produced, or by coloured varnishes, blue, and 

 blue and yellow, and mixed to the tint required. These mate- 

 rials should be applied to the surface of the glass, or interposed 

 between the source of light and the water, in such a way, that 

 the whole of the light which directly illuminates the aquarium 

 may be tinted of the proper colour. In proportion to the quan- 

 tity of light at command and the varying aspect to the sun's 

 rays, so must the transparency of the colouring medium be ad- 

 justed. In my own case I have been obliged partially to employ 

 coloured glass, as the other methods were found to impede too 

 much of the direct light ; but it must be borne in mind that this 

 is in the midst of a crowded city, in a smoky atmosphere, and 

 surrounded by tall houses. To such an extent has this plan 

 succeeded, that several small attached pieces of delicate red sea- 

 weed which I had received in October 1852, and had become 

 thickly mantled with the brown and green confervoid growth 

 already alluded to, and which had not exhibited the least signs 

 of vitality, on being placed in a small glass jar arranged with 

 tinted and oiled tissue paper, soon lost the whole of this parasitic 

 growth, from its gradually decaying and being then consumed 

 by the mollusks, the fronds assuming their deep crimson hue, 

 becoming perfectly clear, and even after so long a period throw- 

 ing out numerous young shoots or leaflets ; and on one of these 

 pieces several beautiful specimens of the Coryne sessilis made 

 their appearance, together with groups of Lepralia and corallines. 



Memorandum 2. 



Another very interesting experiment that I have had pro- 

 gressing very successfully for some time past, is the preserving 

 sea water in a perfectly transparent and healthy state without 

 the use of vegetation of any kind, or, in some cases, even of a 

 scavengerins; mollusk. The adoption of these experiments was 



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