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Bollino Mater an^ IRotifers. 



By C. O. Sonntag. 



A SHORT time ago I happened to come across a green, slimy- 

 looking pond near a farm, which I proceeded to examine 

 with the enthusiasm and joyous anticipation peculiar only 

 to a microscopist. I filled several bottles with the rather unpleas- 

 ant looking fluid before me, and examined it as soon as I got 

 home. It was swarming with what I naturally expected, namely, 

 Eiiglena^ Vorticella^ Amceba^ Brachionus^ Hydatifta, Ste?ifor^ and a 

 legion of ciliated Infusoria. It was indeed a rich find, and at once 

 the idea struck me to seize this opportunity, seeing the material was 

 next to inexhaustible, to try my hand in fixing the organisms in 

 the bottles, and make some permanent slides of them. The 

 specimens represented by the largest number were the Rotifers 

 Brachionus and Hydatina^ and I resolved to experiment exclu- 

 sively upon them, although other organisms would naturally also 

 come in (accidentally) for their share. I examined a few drops in 

 a watch-glass, and noticed that the Rotifers were gorged with 

 food, and therefore not only unpleasant, but unsuitable for careful 

 examination and mounting purposes. I allowed the bottles to 

 stand over night. This allowed all floating extraneous particles 

 to settle to the bottom, and the water became thus tolerably clear, 

 revealing to me next morning not only hundreds, but thousands 

 of busy Rotifers dancing near the surface of the water like so 

 many grains of silversand. 



Through the pocket lens I saw that they were still full with 

 food-particles, and I thought of several means of how to clean 

 them and make them more transparent, but the process was 

 naturally to be a " wholesale one " if it was to be of any use at 

 all. I knew that the use of chemicals was excluded, as these 

 would take more out of the transparent Rotifers than desirable, 

 and would even spoil them altogether. But I thought a good and 

 reliable plan would be to starve them for a day or two, and I 

 carefully poured them from the field bottles into clean water, let 

 them stand for two days, examined them every morning, noon, 

 and night, and was pleased to notice that they gradually became 



