246 THE BIOLOGY OF STENTOR 



CaCl2 and SrCL in the concentrations used by Heilbrunn and 

 found that there was an endoplasmic clotting at the site of injection, 

 hence agreeing with his addendum and general thesis that calcium 

 has a clotting effect. It was especially interesting to me that the 

 clot was moved to the surface and pinched off, as also in amoebas. 

 Even when as much as two-thirds of the interior had been coagu- 

 lated the clot was still ejected and the cortex apparently not 

 violated. 



Swimming of stentors was normal in solutions of CaCL and 

 SrCL, but if the ectoplasm was torn, the wound opened and there 

 was a clotting of the exposed endoplasm, much as in Heilbrunn's 

 surface precipitation reaction. Conversely, in NaCl and KCl tears 

 were never repaired, the endoplasm flowing out of the cut without 

 any sign of coagulation. The responses of Stentor protoplasm were 

 therefore quite like those previously found by the senior author in 

 Amoeba dubia. 



Chambers and Kao also injected phenol-red and bromcresol- 

 purple into their unnamed Stentor and found that the cytoplasm 

 had a pH of 6-8 while that of the macronucleus was at least 7-6. 

 Correspondingly, Strom (1926), using very dilute mixtures of 

 phosphates to obtain a varying pH without specific ionic effects, 

 found that stentors are only slightly influenced by changes of pH 

 from 6-5 to 8-0. 



8. Tests for an antero-posterior metabolic gradient 



In pursuing his theory of metabolic gradients in organisms. 

 Child (19 14) subjected coeriileiis to a respiratory depressant, KCN. 

 The animals were promptly disintegrated, starting from the frontal 

 field and membranellar band and extending posteriorly over the 

 lateral ectoplasm. In a few cases there was a secondary wave of 

 disintegration beginning at the posterior end. The species poly- 

 morphus gave a similar response, though difficult to follow because 

 of the unpigmented cortex. A number of other ciliates also showed 

 graded disintegration of the cell. It was concluded that there is an 

 antero-posterior gradient and that this is metabolic in character. 



On another species (" probably roeselW) Child (1949) used a 

 more subtle approach in studying the intracellular reoxidation of 

 reduced Janus green and methylene blue. Oxidation changes the 

 green dye to red. This color change passed in a wave from the 



