242 THE BIOLOGY OF STENTOR 



distance of fall to excite contraction was then used as a basis for 

 comparison of the reaction of stentors subjected to various drugs. 



Morphine hydrochloride apparently produced the greatest 

 insensitivity. This relaxation was counteracted in a typical manner 

 by the antagonists atropine and picrotoxin. Strychnine produced 

 mild contractions, as would be expected from its effect on higher 

 animals. In curare the contraction was so energetic that both clear 

 and pigmented stripes were said to be torn loose in a way which 

 he did not describe in detail. The antagonist, physostigmin, 

 counteracted this effect. Neresheimer states that these results 

 confirmed earlier studies by Verworn on Stentor, Spirostomum^ and 

 Carchesium. If the myonemes are excitable only through neuroid 

 fibers one might have expected complete paralysis on the basis of 

 blockage of the neuro-muscular junction which curare produces 

 in higher forms. Complete relaxation of specimens which could 

 then be fixed in the extended position was achieved in Spirostomum 

 but not in Stentor. Caffein seemed to increase the sensitivity, but 

 in nicotine the stentors relaxed and became more insensitive. 



A student of mine (N. G. Parisis, 1956, unpubHshed student 

 report), tested the effects of curare and strychnine, separate and 

 combined, on Stentor coeruleus and Spirostomum amhiguum. Both 

 drugs stimulated mucoid secretion, as demonstrated by the obser- 

 vation that the animals could be moved by an advancing needle 

 before the needle came near the cell. In neither substance alone 

 was contractility lost. In a mixture of strychnine and curare, 

 how ever, the ciliates lost their power of contraction completely and 

 could even be cut in two without responding, though the cilia 

 kept beating. 



Neresheimer also tested one bromide (NaBr) which also made 

 stentors so insensitive that they could be cut in two without con- 

 traction, but apparently the effect was not reversible and the 

 animals did not survive the treatment. I have found that 1% 

 solutions of the iodides of sodium or potassium have the same 

 effect and their action is completely reversible (Tartar, 1957a). 

 Outstretched animals could be cut in two without a single twitch 

 in either half, and after returning to normal medium complete 

 contractility was recovered within a day. 



Although they might become very insensitive, Neresheimer 

 found that his treated stentors always contracted when treated with 



