150 



THE AMEEICAN MONTHLY 



[August, 



by washing them off from the slide 

 upon which they are found, or if 

 practicable, by the use of a dipping 

 tube. But a mass of algae or of 

 debris that is supposed to contain in- 

 fusoria of interest is not introduced 

 at random. Such a mass may be 

 dropped in for a few hours and then 

 removed by forceps or dipping-tube ; 

 but it must not remain long enough 

 to decompose. This should never 

 be done in a bottle that already has 

 a variety of living forms in healthy 

 growth, as thereby there is danger of 

 losing them by introducing incompa- 

 tible creatures. 



Sometimes it is desirable to keep 

 a certain specimen found in a jar 

 attached to something as a leaf or 

 stem, separate from the others for a 

 short time. This can readily be done 

 by placing it in a small tube, uncorked, 

 which can be suspended in the jar by 

 means of a thread. In the same way 

 a number of specimens can be select- 

 ed and placed in tubes which can 

 then be suspended in a jar of water 

 and carried about — to a meeting of a 

 society for example — in this way se- 

 curing the advantages of a consider- 

 able quantity of water, while the 

 specimens are easily found. 



The secret of success is in having 

 the plants in the small jars growing 

 well before the infusoria are intro- 

 duced. Even then many of them 

 will not live, for they are very sensi- 

 tive creatures and will not bear well 

 sudden changes in their conditions 

 of life. But perseverance and ex- 

 perience will bring their reward in 

 this as in other things. 



The microscopist who desires an 

 inexhaustable source of entertain- 

 ment, or a rich field for investigation 

 during the winter evenings, can pro- 

 vide for these in no better way than 

 by starting a number of aquaria now. 

 September is the proper time to start 

 aquaria for the winter, and we trust 

 many of our readers will act upon 

 the suggestions of this article, for if 

 they will do so we are sure to hear of 

 many observations they will make. 



Besides the numerous small aquaria 

 the microscopist would do well to 

 have one or two large tanks, holding 

 one or two gallons, in which can be 

 kept a stock of plants and animals of 

 different kinds, and one tall jar in 

 which Vallis}ieria can be grown. In 

 the large tanks should be kept differ- 

 ent water-plants such as Nitella, 

 Ajiacharis, Myriophyllum, Lemna 

 (duck-weed), and others, from which 

 the small aquaria can be replenished. 

 In these may also be kept many mi- 

 croscopic specimens from collections, 

 and especially snails and Daphnia, 

 Cyclops and other entomostraca. The 

 snails may be occasionally introduced 

 into the small jars as scavengers, and 

 the entomostraca can be used to feed 

 the hydras, which will probably be 

 found in one or more of the jars. 



The cyclosis in plant-cells is very 

 beautifully shown in Vallisneria, and 

 this plant can be grown in a tall jar 

 without any care whatever. The 

 roots should be imbedded in mud 

 and sand at the bottom. The 

 plant will grow rapidly and probably 

 fruit in the jar. It will die down in 

 the fall, but in the spring, it will again 

 grow if the roots are undisturbed. 



Naias Flexilis and Cyclosis. 



BY A. C. PALMER. 



On a recent visit to Fresh Pond, 

 Cambridge, about four miles east of 

 Boston, Mass., I made careful search 

 for some of the few and rare sub- 

 merged grasses, or weeds, usually 

 mentioned by microscopists, and in 

 books on microscopy, as best disclos- 

 ing the very interesting phenomenon 

 of the cyclosis, or rotation of fluid in 

 the cells of living plants. Of the 

 plants, the Anacharis alsinastrum and 

 the Vallisneria spiralis being most pro- 

 minent. 



I succeeded in finding the Anacha- 

 ris alsinastrum in abundance, and of 

 a beautiful deep-green color, in full, 

 healthy growth. 



I found also a submerged weed that 

 I had never seen before, and not 



