38 



THE FAMILY AQUAKIUM. 



respect ; and wlien all that remain exhibit unequivocal 

 signs of strength and vitality, you may proceed without 

 hesitation. Perhaps the more exact plan will be to wait 

 patiently until the water, after becoming quite clear, 

 seems, when the sunlight is allowed to fall upon it, to fill 

 with bubbles, which cluster upon the roekwork, as well 

 as upon the bottom and sides of the tank. These bubbles 

 will indicate the oxygenation of the water and the growth 

 of incipient vegetation. They demonstrate, therefore, 

 that your new world is prepared for the animal life you 

 design to bestow upon it. 



Let us, before we leave this branch of the subject, and 

 before we go into the minutiae of propagation in the 

 Aquarium, say a few words in regard to plants generally. 



A plant is philosophically called an organized body 

 without voluntary motion. What it is, practically, we all 

 know, for we can distinguish it (except in some exceed- 

 ingly delicate cases) without difficulty. A plant has its 

 solid and its fluid parts, like all other organized bodies. 

 The cellular substance, the various vessels, the fibres and 

 pith, belong to the former category ; to the latter belong 

 the sap, the air, and the various juices. The juices con- 

 tain nourishment adapted for assimilation into the sub- 

 stance of the plant, and may be called its blood. In 

 many other points, in a physiological sense, there is a re- 

 markable correspondence between the organization of plants 

 and animals. Sometimes this correspondence reaches a 

 point that almost defies human discrimination. Many of the 



