20 PROTOZOOLOGY 



lacustris, Ceratium hirundinella; Sarcodina: Lieberkuhnia wag- 

 neri] Ciliata: Mesodinium pulex, Prorodon discolor, Lacrymaria 

 olor, Amphileptus claparedei, Lionotus fasciola, Nassula aurea, 

 Trochilioides recta, Chilodonella cucullulus, Trimyema compressum, 

 Paramecium calkinsi, Colpidium campylum, Platynematum sociale, 

 Cinetochilum margaritaceum, Pleuronema coronatum, Caenomorpha 

 medusula, Spirostomum minus, S. teres, Climacostomum virens, 

 and Thuricola folliculata; Suctoria: Metacineta mystacina, En- 

 dosphaera engelmanni. 



It seems probable that many other protozoans are able to live 

 in both fresh and salt water, judging from the observations such 

 as that made by Finley (1930) who subjected some fifty species of 

 freshwater Protozoa of Wisconsin to various concentrations of 

 sea water, either by direct transfer or by gradual addition of the 

 sea water. He found that Bodo uncinatus, Uronema marina, Pleu- 

 ronema jaculans and Colpoda aspera are able to live and reproduce 

 even when directly transferred to sea water, that Amoeba verru- 

 cosa, Euglena, Phacus, Monas, Cyclidium, Euplotes, Lionotus, 

 Paramecium, Stylonychia, etc., tolerate only a low salinity when 

 directly transferred, but, if the sahnity is gradually increased, 

 they live in 100 per cent sea water, and that Arcella, Cyphoderia, 

 Aspidisca, Blepharisma, Colpoda cucullus, Halteria, etc., could 

 not tolerate 10 per cent sea water even when the change was 

 gradual. Finley noted no morphological changes in the experi- 

 mental protozoans which might be attributed to the presence of 

 the salt in the water, except Amoeba verrucosa, in which certain 

 structural and physiological changes were observed as follows: 

 as the salinity increased, the pulsation of the contractile vacuole 

 became slower. The body activity continued up to 44 per cent 

 sea water and the vacuole pulsated only once in 40 minutes, and 

 after systol, it did not reappear for 10-15 minutes. The organism 

 became less active above this concentration and in 84 per cent 

 sea water the vacuole disappeared, but there was still a tendency 

 to form the characteristic ridges, even in 91 per cent sea water, in 

 which the organism was less fan-shaped and the cytoplasm 

 seemed to be more viscous. Yocom (1934) found that Euplotes 

 patella was able to live normally and multiply up to 66 per cent of 

 sea water; above that concentration no division was noticed, 

 though the organism lived for a few days in up to 100 per cent 

 salt water, and Paramecium caudatum and Spirostomum amhigu- 



