THE AQUARIUM. 101 



practice will soon enable the collector to distinguish between the 

 murderous crew and the innocent ; but not always, for some of 

 the former positively wear a moveable mask, like the highwaymen, 

 behind which they hide their weapons of offence. An eye should 

 be kept on the aquarium, and any aggressive member of the stock 

 removed by means of a very small muslin net, or a wide glass 

 tube used as a pipette ; an inverted thistle-funnel is useful for this 

 purpose. A few caddis worms (Phryganeidce) should be taken for 

 the quaint appearance of their cases, different species constructing 

 their curious abodes with various material ; only one or two 

 specimens should be included however, otherwise the stock of 

 plants will suffer. Another animal, the water-spider, Argynotea 

 aquatica, deserves a place. It may be found in any pond, running 

 on the'surface, and then disappearing with the metallic sheen of a 

 globule of mercury. When captured, it should be carried home 

 in a box with moist weed, and not in water, for if shaken about in 

 water, it speedily drowns. 



Among the more highly-developed creatures, a few tadpoles 

 deserve a place. In early spring the spawn may readily be found, 

 that of frogs in masses, toads in strings, and newts wrapped in 

 leaves. A few eggs should be placed in the aquarium ; from this 

 the development of the young batrachians is most interesting to 

 watch. 



If it be desired to include fishes, a single specimen, or a pair, 

 male and female, of sticklebacks may be added. If, however, 

 the aquarium be intended as a nursery for microscopic pond 

 life . . this addition is hardly to be recommended. 



For collecting the minuter forms, which in the limit of this 

 note cannot be noticed seriatim, a brother pharmacist adopts the 

 following plan, which we have followed with great success. A 

 small filter bag is made of fine cambric, and fastened to a ring of 

 copper wire, which is afterwards twisted out on each side of the 

 ring, and attached to two long meat-skewers. Arrived at the 

 pond, the skewers are stuck in the bank, supporting the filter be- 

 tween them, and the latter is kept charged with pond water, ladling 

 with a wide-mouthed bottle attached to a stick. By this means, 

 myriads of minute forms of life, such as Hydrse, Desmids, Cyclops, 

 Daphnia, etc., are captured in a few moments ; the ' concentrated 



