240 THE BIOLOGY OF STENTOR 



Merton also tested hydrochloric acid, fatty acids, saponin, and 

 certain alkalis, which produced only injury and no ciliary reversal. 

 Urea and sugars also gave no reversal, and this I can confirm. 



Merton regarded the induced backward movement as a specific 

 effect of the monovalent cations on the cilium. That osmotic effects 

 are not involved is obvious from the fact that the type of ion and 

 not its concentration is crucial. Nor was he dealing with avoiding 

 responses, because he found that stentors show the normal tem- 

 porary backing up even when they encounter calcium chloride, 

 but this compound does not compel the continuous backward 

 movement which KCl does. Also, the reversal in KCl, for example, 

 was not counteracted by adding an equivalent amount of CaCl2. 

 The bearing which these results may have for an analysis of ciliary 

 reversal is yet to be clarified, but to be able to produce reversal, 

 immediate and prolonged, is a beginning. At least we can conclude 

 that the mechanism of body cilia is such that it can adapt to an 

 abnormally continuous backward beating at increased intensity 

 under the influence of reversing agents. 



3. Ciliary anaesthesia 



It has already been mentioned that the heavy metal salt NiS04 

 at very low concentration causes reversible paralysis of both body 

 cilia and membranelles in Stentor, as I found following a suggestion 

 of Gelei (Tartar, 1950). After inducing ciliary reversal, NaCl and 

 KCl also produce partial anaesthesia of the cilia (Merton, 1935) 

 and the potassium salt seems to be the more effective for this use. 



Following early exploratory tests of Verworn, Ishikawa (19 12) 

 obtained reversible narcotization of the cilia in Stentor coeruleus 

 with chloroform vapor. He brought a piece of filter paper soaked 

 in chloroform near the drop containing a stentor in order to quiet 

 the animal for cutting operations, but by his own account this is 

 not to be recommended because necrotic conditions easily develop. 

 At lowest concentrations the stentors showed an accelerated 

 activity, but at higher strengths the cilia were slowed and the 

 animals became semi-elongate. Wounds from cutting were slow 

 in healing. With nearly lethal concentration, the animals remained 

 quiet as if dead, though sometimes they could recover slowly, and 

 it was also reported that they might shed their cilia or begin 

 disintegrating, a small portion at a time. 



