THE CONTRACTILE VACUOLE IN PARAMECIUM TRICHIUM

¹ ZOÖLOGICAL LABORATORY, UNIVERSITY OF PENNSYLVANIA

1. There is an anterior and a posterior contractile vacuolar apparatus in Paramecium trichium.

2. Each is permanent and consists of feeding vesicles, contractile vacuole, excretory tube and pore.

3. The contractile vacuoles of Paramecium trichium are vesicle-fed, differing here from those of other well known species in the same genus which are canal-fed.

4. Diastole of the new vacuole is practically complete before the prolonged systole of the old is over. This gives the appearance of two vacuoles contracting alternately.

5. The excretory tube is long and convoluted with its flattened cup-like end in contact with the contractile vacuole.

6. The excretory tube opens as an excretory pore on the surface of the body opposite the mouth.

7. The pore of the anterior and that of the posterior apparatus are located between the same or adjacent longitudinal rows of cilia.

8. The long duration of systole may be correlated with the presence of the convoluted excretory tube.

9. The excretory tube and pore were first demonstrated by the use of Bresslau's relief staining method.