EVIDENCE ON THE ADAPTATION OF PARAM/ECIA 

 TO DIFFERENT ENVIRONMENTS. 



LORAXDE LOSS WOODRUFF. 



The fact being established that my pedigree culture of 

 Param&cium aurelia (I.) undoubtedly has unlimited power of 

 reproduction without conjugation or artificial stimulation, 1 a 

 culture of Paramcecium caudatum was started for comparison, 

 in order to determine if this animal would show throughout its 

 life history characteristics of specific value and also to determine 

 it it would continue to live and reproduce indefinitely without 

 conjugation or artificial stimulation. 



The results with this culture led me to conclude, as did Jennings 

 and Hargitt, 2 that caudatum is a distinct species. This point I 

 have discussed in a previous paper. 3 The results in regard to 

 the second point arc briefly presented at this time. 



The pedigree culture of Paramcecium caudatum (X.) was 

 started on May 14, 1910, and has been continued under observa- 

 tion to the present time, December i, i<)ii. The methods em- 

 ployed have already been described in detail in earlier papers on 

 pedigree cultures of Infusoria. It is only necessary to state here 

 that the culture was begun by placing a large "wild" individual 

 on a depression slide in about five drops of cuhuiv medium. 

 \Yhen this individual had divided twice, producing four animals, 

 each of these was placed on a separate slide, forming tin- four 

 lines of the culture. Thereafter (until June i, H)ii) a single 

 cell from each of the lines was isolated d.iily in fresh culture 

 medium and the number of divisions during the previous twenty- 

 four hour* was recorded. 



In regard to the culture of I'arannci iiini aurelia (I.), which 



1 L. L. Woodruff: "Two Thousand < < -m -i.itiiui^ of Paramacium." An'liir fiir 

 Prolistenkunde. Bd. 21, 3. 1911. 



-II. S. Jennings and G. T. Harbin: "Characteristics of tin- Divei K.u-i-v ,,i 

 1'aramtrcium." Journ. Morph., Vol. 21. n<>. |. 1010. 



3 L. I.. Woodruff: " Paramiccium aurelia and Paratmecittm ca utlatitin " 

 Morph., Vol. 22, no. 2, 10.11. 



,.. 



