124 ^-^^ Arthur Schaeffer 



I was able to gather from his paper with regard to the method of 

 work our results disagree utterly. 



What is the reason for the disagreement? Metalnikow says 

 that after his paramecia had ceased to take up carmine he stirred 

 up the solution and yet the paramecia refused to ingest any more 

 carmine. In my work I also found this to be true, but I attributed 

 this to the fact that the carmine is no longer mixed in the same 

 wav as it was originally, for the mucus excreted bv the paramecia, 

 and other colloidal matter in the water, cause the carmine particles 

 to stick together, so that the paramecia no longer take this kind of 

 carmine with readiness. Further Metalnikow states that if one 

 takes some of these paramecia which have refused to eat carmine 

 and places them in fresh carmine, none is taken up. I have 

 also tried this many times, but in almost every case I found that 

 the paramecia again took up fresh carmine. In some few cases I 

 found paramecia which did not eat carmine under any circum- 

 stances, even if they were placed in fresh solutions, but close exami- 

 nation nearly always showed that these rare individuals either 

 w^ere deformed or had just previously divided, and so were unable 

 structurally to ingest the grains of fresh carmine. It appears 

 possible that Metalnikow^ unfortunately got hold of some of these 

 individuals. 



But there is another statement in his paper which is hard to 

 reconcile with the one quoted above. 



"Halt man die Infusorien bei massig hoher Tempera tur (d. h. 

 bei 10-15° C; die Versuche wurden wahrend der kalten Jahres- 

 zeit angestellt), so tritt wahrend mehrere Tage keine Theilung ein. 



"Jeden Tag untersuchte ich ein solches ungeteiltes Iniusor auf 

 seine Fahigkeit hin Karmin zu verschlucken. Im Verlauf von 

 zwei, dre (in seltenen Fallen auch 4) Tagen, wahrend welcher 

 Zeit es mir gelungen war die Infusorien von einer Theilung abzuhal- 

 ten, konnte ich nicht bemerken, dass ihr Verhalten zum Karmin 

 irgend welche Abanderungen erfahren hatte. Jeden Tag weiger- 

 ten sich die Infusorien hartnackig Karmin zu fressen. Kaum aber 

 hatte sich ein Infusor geteilt, so anderte sich sein Verhalten 

 plotzlich und es begann von neuem Karmin zu fressen. In den- 

 jenigen Fallen wo ich das Infusor in den Thermostat oder an 



