112 THE SEA-SIDE AND AQUAEIUM. 



have had them live for months. For a long time, I 

 was much puzzled at this. Experience, however, has 

 solved the mystery; and as my young friends may 

 derive benefit from my labours, I shall proceed to 

 enlighten them upon the philosophy of the tank, 



I found, then, that if, when I saw the Crab leave 

 its shell, I took it up and placed it in a cup full of 

 water, dipped gently out of the Aquarium, that it 

 generally in a short time revived, and was as lively 

 as ever. Why should it live in one place, and not 

 in the other? the water was the same. The same 

 in appearance only, but in reality very different; the 

 one being much salter than the other, and the ani- 

 mals, being suddenly immersed in a fluid the density 

 of which was so different to what they had been ac- 

 customed, could not live in it any length of time; 

 whereas the consistency of the water taken from the 

 upper portion of the tank would perhaps be* the same 

 as in their own rock pool. 



When so situated, I would advise the young aqua- 

 rian to syringe the water well ; then, while the whole 

 is disturbed, to hold a saucer inverted in his left hand 

 above the tank, and, with a caraffe of fresh water in 

 his right, pour about a tumbler over the saucer, or 

 more, according to the size of the Aquarium. When 

 the water is clear again, place in the Soldier-crabs, 

 and they will no longer need to dread their saline 

 enemy; for he, having been subdued by your pro- 

 cedure, will become their best friend, the preserver of 

 their very existence ! 



