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The Activity of the Contractile Vacuole of Crithidia fasciculata *
Author(s) -
COSGROVE WILLIAM B.,
KESSEL RICHARD G.
Publication year - 1958
Publication title -
the journal of protozoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 0022-3921
DOI - 10.1111/j.1550-7408.1958.tb02569.x
Subject(s) - contractile vacuole , vacuole , crithidia fasciculata , chemistry , osmotic pressure , biophysics , volume (thermodynamics) , biochemistry , biology , thermodynamics , physics , dna , cytoplasm
SYNOPSIS. It has been shown that the output of the contractile vacuole of Crithidia fasciculata increases as the concentration of solute in the external solution decreases when NaCl is the solute. The increase in output is the result of increased rate of growth as well as increased maximum size, the latter being more important in the range 0.1M–0.01M. Solutions of penta‐erythritol produce the same effects as isosmolar solutions of NaCl. Body volume is not maintained constant but increases less than two‐fold between 0.1M and 0.0001M. The isotonic concentration of NaCl is estimated as 0.12M. It is not possible to demonstrate any effect of concentration of the external environment on the endogenous rate of oxygen consumption. A linear relationship between output and calculated osmotic gradient across the cell membrane has been shown in the concentration range 0.1M–0.01M. Absence of this relationship, and failure of body volume to increase as predicted, in solutions more dilute than 0.01M are interpreted as indications that other processes probably become predominant in these solutions. It is concluded that the contractile vacuole of this flagellate is incapable of maintaining absolute constancy of internal osmotic pressure and body volume but prevents much of the change expected on physical grounds.