THE FRESH-WAEER AQUARIUM. 
39 
fresh-water plants we have for the most part to deal with the dif¬ 
ferent shades of green, while in salt-water plants the colors are 
varied and brilliant. There is, however, this advantage in fresh¬ 
water plants, that almost all of them will grow well in a properly 
managed aquarium, while only the very green ones of the salt¬ 
water plants are likely to flourish under the same conditions. One 
great drawback to the growth of aquarial plants is the change of 
the water from a higher to a lower temperature, or the reverse. 
It is also sometimes found difficult to grow several kinds in one 
tank successfully. The common water-cress (Nasturtium offi¬ 
cinale.), for example, found mostly in cold springs and their 
brooks, will do well with water; starwort (CalUtricoe verna), a 
plant growing in a similar situation, if the water in the tank is 
kept at a low temperature ; but at a moderately high one growls 
long and rank, and finalty decays. So again many plants which 
grow in brooks or rivers, and have become accustomed to be con¬ 
stantly moved by a current, when placed in the still water of an 
aquarium inevitably mould away. 
The question is often asked wdiat kinds of plants are the best 
for the aquarium, and where are they found? Most writers on 
this subject give long lists of plants, which are useless to those 
who are unacquainted with the botanical names. To the majority 
of people not even the common names of most water plants are 
known, and to such it becomes very perplexing to make a selection 
from a list bare of any description. Although it is insisted by 
some that the tank should not be filled with every kind of plant 
that the collector can obtain, yet it seems as if there was no 
sound reason why all the plants that flourish in the aquarium 
should not be placed therein. In a properly managed aquarium 
there are very few water plants which will not do well; the few 
exceptions being found in the lilies, which require a deeper soil 
than is convenient in the tank, and in those plants accustomed to 
a lower temperature of the water than is easy to maintain. Apart 
from these take any of the green plants found in ponds, and 
placing them in the tank, watch their growth, and a few weeks 
trial will determine their value whether they are of use or for 
ornament. It is hardly practicable to arrange the plants in the 
tank in botanical order, the room is so limited. A better way, if 
we wish such an arrangement, would be to devote a separate tank 
to each variety. This could easily be done in what is called the 
