Page:The Book of the Aquarium and Water Cabinet.djvu/125

Rh near rivers; the small tributaries of the Lea, and the dykes that abound in the marshes at Tottenham, supply me with specimens whenever I seek them.

Among the water-worms most easily obtained, the hair-like Gordius aquaticus (Linnæus), and the curiously-formed Nais, may be recommended as curious and interesting. The latter requires a bottom of sand in which to burrow, and should be covered with only a few inches of water. When it takes to its new home, it plunges its body into the sand or mud, and extends its telescope-tail upwards to the surface for air, adapting its length to the depth of the water.

The generation and development of reptilia and mollusca may be better studied by the use of jars for the specimens, than by their immersion in the aquarium. Tadpoles, the larva of newts, and the spawn of mollusks, may be preserved in the cabinet for purposes of study, much better than in the tank; each species being separate in a bright and portable vessel, every minute change can be observed, and a lens applied at any time, or the specimens removed for close inspection without difficulty. I find it a good practice to remove any spawn, which may be deposited on the large vessels, to the small jars on my shelves. There the little Lymnea and Planorbis are developed in hundreds, without molestation; and if increase of Paludina vivipara be required, a jar is at once converted into a breeding tank by throwing a couple into it, with a bunch of Callitriche, and any vegetable waste from the tanks. In the aquarium, the young mollusks are devoured almost as soon as they are born; and the