24 PROTOZOOLOGY 



posing organic matter are frequently found in the faecal matter of 

 various animals. Their cysts either pass through the alimentary 

 canal of the animal unharmed or are introduced after the faeces are 

 voided, and undergo development and multiplication in the faecal 

 infusion. Such forms are collectively called coprozoic Protozoa. The 

 coprozoic protozoans grow easily in suspension of old faecal matter 

 which is rich in decomposed organic matter and thus show a strik- 

 ingly strong capacity of adapting themselves to conditions different 

 from those of the water in which they normally live. Some of the 

 Protozoa which have been referred to as coprozoic and which are 

 mentioned in the present work are, as follows: Scytomonas pusilla, 

 Rhynchomonas nasuta, Cercomonas longicauda, C. crassicauda, Tre- 

 pomonas agilis, Naegleria gruberi, Acanthamoeba hyalina, Chlamy- 

 dophrys stercorea and Tillina magna. 



As a rule, the presence of sodium chloride in the sea water prevents 

 the occurrence of numerous species of fresh-water inhabitants. Cer- 

 tain species, however, have been known to live in both fresh and 

 brackish or salt water. Among the species mentioned in the present 

 work, the following species have been reported to occur in both fresh 

 and salt waters: Mastigophora: Amphidinium lacustre, Cerat- 

 ium hirundinella; Sarcodina: Lieberkiihnia wagneri; Ciliata: Meso- 

 dinium pidex, Prorodon discolor, Lacrymaria olor, Amphileptus 

 claparedei, Lionotus fasciola, Nassula aurea, Trochilioides recta, 

 Chilodonella cucullulus, Trimyema compressum, Paramecium cal- 

 kinsi, Colpidium campylum, Platynematum sociale, Cinetochilum 

 margaritaceum, Pleuronema coronatum, Caenomorpha medusula, 

 Spirostomum minus, S. teres, Climacostomum virens, and Thuricola 

 folliculata; Sxictoria, : Metacineta mystacina, Endosphaera 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 marinum, Pleuron- 

 ema jaculans and Colpoda aspera are able to live and reproduce 

 even when directly transferred to sea water, that Amoeba verrucosa, 

 Euglena, Phacus, Monas, Cyclidium, Euplotes, Lionotus, Para- 

 mecium, Stylonychia, etc., tolerate only a low salinity when directly 

 transferred, but, if the salinity is gradually increased, they live in 

 100 per cent sea water, and that Arcella, Cyphoderia, Aspidisca, Ble- 

 pharisma, Colpoda cucullus, Halteria, etc. could not tolerate 10 per 

 cent sea water even when the change was gradual. Finley noted no 



