62 



THE NATURALIST, 



should be taken to keep the vase well filled with fresh water for some days, 

 (to be changed frequently) until all the deposit dissolved out of the cement 

 has quite disappeared ; and no animal or vegetable life should be placed in 

 it until this is completed, otherwise they will quickly die off. Mine being 

 thus previously prepared I filled it with artificial sea-water made as follows : 



To one gallon of pure spring water add : — - 



Common salt, 3^ ozs. 



Epsom salts, ^ oz. 



Chloride of Magnesium, 200 grains. 



Chloride of Potassium, 40 grains. 



After these salts have been well stirred about in the water it must be 

 strained through a piece of muslin. 



The sea-weeds to be put in the aquarium should be such as are attached 

 to bits of stone ; the best for thriving being the most sombre coloured ones, 

 — avoid all the red ones — take the dark-brown and green ones — the former 

 of which I have found to be best. 



In my aquarium which was fitted up last September, and has never had 

 the water changed since, I placed some tliree or four pieces of rock having 

 weed attached at the bottom ; which, may be advantageously covered over 

 with clean small pebbles. As I have not studied Algology much I cannot 

 with certainty name the species I put in, — I think they were Dictyota 

 didiotoma, Desmarestia acvleata, and one or two others which I was unable 

 to name. This hoAvever is not of much importance in my case, as there is 

 but little of any of them left. The animals put in were of no great 

 rarity, but such as may be picked up in almost any tide pool. There were 

 three or four Actiniae, A. mesemhryantlieinum ; two limpets, Patella vulgaris; 

 five or six whelks, Purpura lapillus ; and one Chiton. 



Of the sea-weeds all except one Desmarestia gradually withered away and 

 had to be taken out, so that by the end of December, there was none of the 

 original stock left, except the one above mentioned ; but this continued in 

 good health and seems to be an excellent ox^^gen producer. In a paper I 

 recently read by Mr. Shirley Hibberd, respecting his fresh water aquarium, 

 he says, that he never put any plants into it, but left it to nature who soon 

 supplied in the shape of Confervoe, &c., what she required. My own expe- 

 rience as far as it goes, is quite in accordance with this, as although, I placed 

 some sea-weeds in the vase they soon withered away, but now there is a 

 growth of new forms which seem quite sufficient to maintain the balance : 

 every stone bristles with this minute vegetation, and every branch of it 



