ECOLOGY 31 



developing in invertebrates which feed upon the blood of vertebrates 

 as source of food supply, will have opportunities to establish them- 

 selves in the higher animals. 



References 



Calkins, G. N. and F. M. Summers (editors). 1941 Protozoa in 

 biological research. New York. 



Chalkley, H. W. 1930 Resistance of Paramecium to heat as af- 

 fected by changes in hydrogen-ion concentration and in inor- 

 ganic salt balance in surrounding medium. U. S. Publ. Health. 

 Rep., Vol. 45. 



Cleveland, L. R. 1926 Symbiosis among animals with special 

 reference to termites and their intestinal flagellates. Quart. Rev. 

 Biol., Vol. 1. 



1928 Tritrichomonas fecalis nov. sp. of man; its ability to 



grow and multiply indefinitely in faeces diluted with tap water 

 and in frogs and tadpoles. Amer. Jour. Hyg., Vol. 8. 



Dallinger, W. H. 1887 The president's address. Jour. Roy. Micr. 

 Soc. for 1887. 



DoBELL, C. 1918 Are Entamoeba histolytica and Entamoeba ranarum 

 the same species? Parasitology, Vol. 10. 



DouDOROFF, M. 1936 Studies in thermal death in Paramecium. 

 Jour. Exp. Zool., Vol. 72. 



Efimoff, W. W. 1924 Ueber Ausfrieren und Ueberkaltung der 

 Protozoen. Arch. f. Protistenk., Vol. 49. 



Finley, H. E. 1930 Toleration of freshwater Protozoa to increased 

 salinity. Ecology, Vol. 11. 



Glaser, R. W. and ISF. A. Coria. 1933 The culture of Paramecium 

 caudatum free from living microorganisms. Jour. Parasit. Vol. 

 20. 



Janda, V. and 0. Jirovec 1937 Ueber kiinstlich hervorgerufenen 

 Parasitismus eines f reilebenden Ciliaten Glaucoma piriformis und 

 Infektionsversuche mit Euglena gracilis und Spirochaeta hiflexa. 

 Mem. soc. zool tehee, de Prague, Vol. 5. 



Kidder, G. W. 1941 Growth studies on cihates. VII. Biol. Bull., 

 Vol. 80. 



Kolkwitz, R. and M. Marsson 1909 Oekologie der tierischen 

 Saprobien. Intern. Rev. Ges. Hydrobiol. u. Hydrogr., Vol. 2. 



Kudo, R. R. 1929 Histozoic Myxosporidia found in freshwater 

 fishes of Illinois, U.S.A. Arch. f. Protistenk., Vol. 65. 



Lackey, J. B. 1925 The fauna of Imhof tanks. Bull. New Jersey 

 Agr. Exp. Stat., No. 417. 



Lauterborn, R. 1901 Die "sapropelische" Lebewelt. Zool. Anz., 

 Vol. 24. 



Needhum, J. G., P. S. Galtsoff, F. E. Lutz and P. S. Welch. 1937 

 Culture methods for invertebrate animals. Ithaca, N.Y. 



Noland, L. E. 1925 Factors influencing the distribution of fresh- 

 water ciliates. Ecology, Vol. 6. 



