MICHIGAN ACADEMY OF SCIENCE, 37 



Tape-grass (Valis neria). Eggeling and Ehrenberg, pp. 46 and 48. 



Mermaid weed (Proserpinaca plustris). Eggeling and Ehrenberg, pp. 

 35 and 56. 



Water crow-foot (Ranuuculus aquatilis ). Eggeling and Ehrenberg, 

 p. 62. 



Pond-weed (Potaino(jeton perfoliatus ). Eggeling and Ehrenberg, p. 55. 



The roots of the plants should be brought in when possible, but it 

 will be found that stems carefully planted will soon root and thrive in 

 the new location. No rule can be given as to the exact number of plants 

 to introduce into an aquarium of a certain size, but it is an observed 

 fact that there is greater danger of planting too few than too many. 

 Where stems alone are used it will be found necessary to weight down 

 the lower ends. This may be done very satisfactorily by means of small 

 strips of lead a quarter of an inch or less in width. The strips should be 

 bent rather loosely about the base of the stems and buried with them 

 well down in the sand. Several stems or plant slips may be planted 

 together, weighted down by the same piece of lead. Crowding in this 

 way, however, should \h^ avoided as there is a greater tendency for the 

 stems to decay. The plants should be thoroughly washed, preferably in 

 running water and may even profitably be sterilized before being intro- 

 duced into the aquarium. Osburn (1914) suggests immersing tliem for 

 ten to fifteen minutes in a solution of creolin (two teaspoonfuls to a 

 gallon of water). This washing and sterilizing process will not only 

 get rid of much dirt but will also lessen the danger of undesirable algae 

 and many forms of parasitic life. 



After the plants have been arranged the aquarium is ready for water. 

 For this purpose clean river, creek or pond water is best, but moderately 

 liard tap-water (not chemically treated) or rain water (not cistern) may 

 be used. The water sliould be poured in gently or if tap-water is used 

 it should be allowed to flow slowly through a tube in such a way as not 

 to disturb the plants. If the sand and gravel have been thoroughly 

 washed, the water should not be roiled by this process. The tank should 

 be filled to within two to four or five inches (depending somewhat upon 

 size) of the top. Debris collected at the surface may be skimmed off 

 with a spoon or the tank may be allowed to overflow and the surplus 

 water either dipped or siphoned out. Floating plants such as "duck- 

 weed" should now be introduced. The tank should be kept covered to 

 prevent evaporation and the entrance of dust; for this purpose a glass 

 cover is better than any other because of its advantage for observation 

 purposes. It should be placed where it will receive plenty of light — 

 preferably but not necessarily, north light. Bright sunlight should be 

 avoided and a temperature ranging from 50 to 70 degrees Fahrenheit 

 (Osborn, 1914) is desirable. It is better to leave the aquarium undis- 



