.1882.] 



MICROSCOPICAL JOURNAL. 



149 



For the microscopic specimens a 

 small bottle, holding about 6 ounces, 

 with square sides, makes an excellent 

 aquarium. Such bottles should be 

 about two-thirds filled with water, 

 and covered to exclude dust. We 

 have used the tin-foil that tobacco is 

 wrapped in to cover them, and found 

 it well adapted to the purpose. Sever- 

 al of these bottles should be kept 

 with sprigs of water-plants growing 

 in them, so that whenever an inter- 

 esting specimen is found it can be 

 put into one of them, to grow and 

 multiply by itself. In this way it is 

 sometimes possible to cultivate micro- 

 scopic forms of life very successfully. 

 We have thus grown hundreds of the 

 common rotifers and kept them for 

 weeks in the winter time. That was 

 done, however, in a one-ounce bottle, 

 which had a small bit of Nitella in it. 

 We have also kept Volvox in fine con- 

 dition for many days in a small bottle 

 covered with a watch-glass. 



Beginners in this work are apt to 

 put too much material into their jars. 

 A very small bit of a vigorously grow- 

 ing plant will suffice, and if too much 

 is introduced, it will soon loose its 

 vigor, and some of it will decay and 

 make the water impure. 



The jars should not be disturbed 

 much, and when they are moved they 

 should be handled carefully and then 

 replaced as they stood before, in order 

 to ensure uniform conditions of light 

 and temperature. 



We have seldom been troubled 

 with an excessive growth of unicellu- 

 lar algae on the sides of our jars. 

 Usually these come from an excess 

 of light. But a filamentous Clado- 

 phora found its way into one of our 

 larger jars more than a year ago, and 

 it became such a nuisance that finally 

 the jar was given over to that plant 

 entirely, and is now green with it. 

 When the jar is wanted for other 

 use it must be washed in boiling 

 water to get rid of the too prolific 

 alga. When minute algae do come in 

 such abundance as to be troublesome, 

 set the jar in a dark closet for a 



few days and they will disappear. 



However, for microscopic purposes 

 such growths are not usually objec- 

 tionable, for some of the infusoria 

 delight in them, and it is not neces- 

 sary to keep the sides of the small 

 bottles clear, as in the case of larger 

 aquaria. Nevertheless, they should 

 not be allowed to increase too much, 

 for if they do they may suddenly fill 

 the water with a cloud of swarm- 

 spores, and bring about a decomposi- 

 tion which will kill everything therein. 

 Such a condition of affairs, if threat- 

 ened, can be prevented by removing 

 the jar a short distance from the win- 

 dow, when growth will be less rapid. 



It does not seem to be a matter of 

 much consequence what plants are 

 used in the microscopist's aquaria. 

 Nitella is a clean and hardy plant, 

 and we have usually preferred it. 

 One or two stems, a couple of inches 

 long, is enough. Anacharis is also 

 excellent for the purpose ; Myrio- 

 phyllum would doubtless prove quit^ 

 as good, and perhaps even better, for 

 it is a plant with leaves well adapted 

 as a resting place for the tube-bearing 

 rotifers. Besides these we have Cera- 

 tophyllum, Callitrichia, Utricularia, 

 Naias, and Potamogeton, and some 

 persons prefer Ceratophyllum above 

 all other plants for the aquarium.* 



As for the stocking of small aqua- 

 ria, the only precautions are, not to 

 put in too much material and not to 

 put in animalcules that will kill each 

 other. Our plan is as follows : When 

 we have a collection of pond-life, 

 plants and animals of all kinds all 

 together, we put the whole mass intp 

 a saucer of water and let it remain 

 there until it is convenient to look it 

 over. In a saucer the collection will 

 keep fresh while in a bottle it would 

 soon become foul. Then, in looking 

 over it with the microscope, the ani- 

 malcules that it is desired to keep 

 are transferred to the bottles, either 



* As many collectors may not be able to 

 distinguish these plants, we purpose to giv^ 

 illustrations of some of them as soon as the 

 cuts are ready. — Ed. 



