4538 Notes on Animals in small Aquaria. 



coloured media, and thus all the results observed in the vegetation, 

 and much even of the healthy animal life of deep sea water could be, 

 under this arrangement, assimilated ; and this, 1 am happy to state, 

 has proved experimentally to be the case, so that, by very 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 animal 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 transparent, at others the 

 sheets of paper being superposed until the desired effect was pro- 

 duced, or by coloured varnishes, blue, and blue and yellow, and mixed 

 to the tint required. These materials 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 quantity of light at command and the varying aspect to the sun's 

 rays, so must the transparency of the colouring medium be adjusted. 

 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, 185*2, 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 con- 

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

 becoming perfectly clear, and even after so long a period throwing 

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

 several beautiful specimens of the Coryne sessilis made their appear- 

 ance, together with groups of Lepralia and corallines. 



