1923] Contractile Vacuoles in Amoebae 55 



Summary 



1. Salt water amoebae were kept on a mecliiim made up with 

 fresh water for six days. 



2. On this fresh water medium they developed 1, 2, 3, and 4 con- 

 tractile vacuoles. 



3. The rate of contraction of the vacuole in fresh water amoebae 

 was more rapid when they were grown on 2.5 per cent agar medium, 

 than when they were grown on 0.5 per cent agar medium. 



4. The older the culture of the amoebae the slower was the rate 

 of contraction of the vacuoles. 



5. The more active the amoeba is the more rapid is the pulsation 

 of its vacuole. 



6. The rate of contraction of the vacuole varies in the different 

 strains of amoebae used. 



North Carolina College for Women, 

 Greensboro, N. C. 



BIBLIOGEAPHY 



1. Hogue, M. J., 1914: Archiv f. Protisteiikimde 35: 154. 



2. Zuelzer, M., 1910; Archiv f. Ent. Mech. 29. 



3. Haiice, E. T., 1917: Jouni. Exp. Zool. 23: 287. 



4. Calkins, G. N., 1901: The Protozoa. 



5. Hogue, M. J., 1917: Journ. Exp. Zool. 22: 565. 



