430 Gary N. Calkins. 



g. Apple Juice. A piece of fresh Porter apple was allowed to 

 lie for a few minutes in the hay infusion. In this case the result 

 was well marked, and a decided stimulus was noted. Again, on 

 Sept. 20, A5, A6, A7 and A8 were all put into one drop of apple 

 juice to 12 drops of hay infusion and left for thirty to forty-five 

 minutes. They were then transferred to clear hay infusion and 

 left. All divided the next day. The experiment was repeated on 

 the 2 1st with a like result. In some cases the organisms died 

 immediately, showing that the strength used was too great. When 

 properly diluted, however, apple seemed to give a satisfactory 

 temporary stimulus, although in no case did the stimulation last 

 for more than forty-eight hours. The same experiment tried in 

 October gave no results; the organisms died. 



In addition to the above, various proprietary mixtures were 

 tried from time to time. Among these were phospho-albumin, 

 and nuclein-albumin; none gave satisfactory results. 



2. Experiments with Acids and Salts. 



In view of the successful results which have followed experiments 

 with ions in connection with egg development, it was thought that 

 perhaps dilute acids or salts would have a beneficial result in the 

 case of these weakened infusoria. Normal solutions were made in 

 each case and various strengths were tested from those that would 

 kill to those that only slightly stimulated. The organisms were left 

 in the fluids for only a short time (20 to 30 minutes) and were then 

 transferred to fresh hay infusion. Attention may be called here 

 to the fact that potassium phosphate when used in this way was 

 successful in restoring the vitality of weakened Paramcecium in 

 the preceding December cycle, the "rejuvenation" which resulted 

 was directly comparable with that eff^ected by the beef extract. 

 There was reason, therefore, to believe that the repeated use of 

 various salts would give satisfactory results in the last period of 

 weakness of the race. This expectation, however, was not real- 

 ized for none of the chemicals used in the fall and winter of 1902 

 was successful in this way; all were as futile as the beef and pan- 

 creas extract, as shown by the following experiments: 



