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BULLETIN OF THE UNITED STATES FISH COMMISSION. 
The passive limnetic forms included in the preceding list are: 
Oikomonas termo, on floating floccose material. Zoothamninm arbitscula, on floating material. 
Colacium steinii, on Diaptomus. Yaginicola crystaUina (?) on Fragillaria. 
Colaciumvesiculosum, on Cyclops. Acineta mystacina, on floating floccose material. 
Vorticella rhabdostyloides, on Anabana. 
The following species may be noted as of special interest because of their fitness 
as objects of investigation in experimental or other lines: 
Chilomonas paramecium is a fiagellate form that can always be procured in unlim- 
ited numbers by simply allowing the aquatic plants to decay in jars. The necessity 
for large numbers in carrying on experimental work needs no emphasis. The ease with 
which a Protozoan can be cultivated in the laboratory is almost the most important 
element in its availability for investigation. 
The species of Euglena , Phacus, and Trachelomonas are always to be had in large 
numbers from East Swamp, South Bass Island. 
Trachelitis ovum , Dileptus miser, and Nassula. ornata are ciliates which are valuable 
for certain sorts of work on account of their large size. The same is true to a more 
pronounced degree of Spirostomum ambiguum , and especially of Bursaria truncatella. 
The latter is an enormous creature for a unicellular animal, being a millimeter or more 
in diameter. It could thus be handled in the same individual way as many of the 
large Metazoa. This animal was always procurable in small numbers from the swamp 
near the fisli-hatchery on South Bass Island. Doubtless a little experimentation would 
discover a means of cultivating them in large numbers. Perhaps there is no other 
Protozoan that would be so favorable an object for an investigation into the effects of 
localized stimuli and into the question of the localization of functions in the Protozoan 
body or related problems. 
Other ciliates that could always be procured in large numbers are Glaucoma 
scintillans , Colpidium cucullus , Paramecium caudatum , Urocentrum turbo , Cyclidium 
glaucoma , and Vorticella convallaria. 
For Rhizopoda, three species of Difflugia — 1). globulosa , 1). lobostoma , and D. 
corona — are particularly abundant and might be used for work on this group. Cul 
tures properly managed usually resulted in obtaining large numbers of various species 
of Amoeba. 
Species of Volvox, Eudorina , Pandorina , etc., swarm in East Swamp, South Bass 
Island; they are not included in the foregoing list. A study of the physiology of 
these creatures, transitional as they are between Protozoa and Metazoa, promises 
much of interest. 
Dartmouth College, Hanover , N. //., May 25 , 1899. 
