STRUCTURE OF PROTOPLASM OF PARAMCECIUM. 2Q 



Hardy observed the same secondary reversed movement of the 

 colloidal particles as has been observed in the reaction of Para- 

 mcecium. All these facts make very evident the similarity which 

 exists between the electrical conditions in the 'two solutions. 

 Lillie ! has observed a similar relation between the response to 

 the electric current and the chemical condition of the protoplasm 

 whether acid or alkaline, in his experiments upon nuclear and 

 cytoplasmic structures cited at the beginning of the paper. He 

 shows, that, when exposed to the electric current, nuclear struc- 

 tures, which contain a large amount of nucleic acid, move toward 

 the anode, while cells very rich in cytoplasm, which is basic in 

 reaction, move toward the cathode. 



3. Chemota.\is. A large number of important contributions 

 have been made during the last few years to our knowledge of 

 the reaction of protozoa to chemical stimuli. Most notable have 

 been the remarkable series of investigations carried on by Jen- 

 nings, who has given us not only a complete account of the sense 

 of the reaction of many protozoa to a wide range of chemical 

 substances, but also an accurate description of the method of the 

 reaction in each case. My own results agree with those of Jen- 

 nings in all essential points. I confirm his account of the " motor 

 reaction" of Paramcecium when under a chemical stimulus. It 

 was not my purpose to repeat any of Jennings' experiments, but 

 only to ascertain the chemotropic reactions of Paramcecium under 

 various conditions, to see if they could be modified by external 

 influences as was the galvanotropic response. The only respect 

 in which my conclusions depart from Jennings' is that my experi- 

 ments seem to show that the chemotropic reactions of Paramcecium 

 which he describes are not of universal occurrence, but limited to 

 paramoecia which have been reared under definite chemical sur- 

 roundings. In other words, the sense of the chemotropic reac- 

 tion, like the galvanotropic, depends upon certain chemical con- 

 ditions of the environment. 



Jennings found that paramoecia were in general positive to 

 weak acids (/. e., formed a gathering within the drop) and nega- 

 tive to weak alkalis. He also observed that they reacted in a 

 constant manner to a large number of salts. In my own experi- 



1 Lillie. loc. cif. 



