ANALYSIS OF STENTOR 249 



Stimulated the animal to great activity, accelerated division with 

 production of many smaller cells, and gave no acquired immunity 

 to higher concentrations. The resistance of this stock w^as already 

 high but Daniel showed that this did not obscure a fundamental 

 lack of acclimatization. 



In the second stock, animals in i % ethanol were also excited to 

 increased activity but showed practically no increase in rate of 

 division, and they acquired a marked immunity as a result of 

 remaining in this weaker solution. For example, in 6% solutions 

 they died in 162 seconds if not acclimated but lived for 301 seconds 

 if pre-treated for 4 days in 1% ethanol. 



If acclimated, 6% ethanol made the membranelles beat so 

 vigorously that the whole cell shook. The acquired tolerance was 

 a function of the strength of the acclimating solution and the length 

 of time the animals were exposed to it, appreciable immunity being 

 obtained by 4 hours ; with no further increases after 4 days exposure 

 to sub-lethal concentrations. 



All stentors were killed in 8% ethanol. The membranellar band 

 and frontal field were the last parts to become quiet and begin 

 disintegration. Acquired tolerance for ethanol was not transferable 

 and gave no increased immunity to methanol. 



In I to I /4th molar glycerine, pigment was not shed as in the 

 alcohols. Stentors remained motionless and then suddenly con- 

 tracted, whereupon the membranellar band was shed as a ribbon. 

 If rescued from the solution, survivors could then regenerate a 

 new set of feeding organelles. Otherwise the animals plasmolyzed, 

 beginning at the posterior end. Ethanol immunity was not trans- 

 ferable to glycerine and indeed only made the animals more 

 sensitive to the latter. Hence in general Daniel regarded his 

 findings as demonstrating Ehrlich's principle that immunity is 

 specific and non-transferable. 



Daniel also found, as had Peters (1904), that stentors are not 

 tolerant to excess alkali or acid, and this has also been my 

 experience. Even very dilute solutions of hydrochloric acid pro- 

 duced rapid killing after the membranelles stopped beating and 

 pigment was shed. Apparently sodium hydroxide does not pene- 

 trate the cell so rapidly, and stentors could live for a remarkably 

 long time if the pellicle was not ruptured. The alkali caused a loss 

 of membranelles as in glycerine and the shed pigment became a 



