THE FRESH- WATER AQUARIUM. 



S5 



but are very useful. From the close manner in which they 

 cover the water, they have been named Lenina — from 

 le;pis, a scale. The duckweeds produce a capital shade in 

 an Aquarium, so as to screen the animals from the sun, 

 and harbor a host of minute creatures that provide an 

 ample game-preserve for the fish, etc., as well as a wide 

 field for the inquisitive observer, if armed with a good 

 microscope. The surface of any pond will furnish you 

 with duckweed, and as it is a floating plant altogether, 

 it need only be thrown into the tank, where it will estab- 

 lish itself a home and spread rapidly. As it looks best in 

 a mass, the loose pieces might be picked out and rejected 

 with advantage. 



No. 19. Common Dock is too large a plant for our 

 purpose. It may be seen along the margin of rivers, has 

 a stout root, alternate and often entire leaves, and bears 

 panicles of small greenish flowers. There are about 

 sixty varieties, five or six of which are natives of America. 

 Dock is somewhat esteemed in medicine. 



No. 20. Common Rush needs little or no description. 

 It is a sedge-like plant, chiefly growing in marshes, with 

 inconspicuous greenish flowers. It is botanically called 

 the Jimcus. The soft rush, or J. effusus, is remarkable for 

 its tufts of long, awl-shaped leaves and stems, looking 

 something hke the spines of a porcupine, with flowers in 

 loose, lateral panicles. These are the leaves and stems 

 used in making mats, etc. The J. scirpuSj or club-rush, 

 is common in manshes. Its flowers are disposed in little, 



