ECOLOGY 21 



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 are 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- 

 yomonas agilis, Dimastig amoeba gruheri, Acanthamoeba hyalina, 

 Chlamydophrys stercorea and Tillina magna. 



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

 the occurrence of the large number 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 lacustris, Cerat- 

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

 dinium pulex, 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 

 follicidata; Snctoria: 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 marina, 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, Styl onychia, 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 

 morphological changes in the experimental protozoans which might 

 be attributed to the presence of the salt in the water, except Amoeba 



