1 86 



LOUISE H. GREGORY. 



of sodium used was that found by Packard to cause a definite 

 increase in the division rate of Paramecium. The same amount 

 was also used by Austin in her experiments with the life history 

 of Uroleptus. This amount was approximately a N/jooo solu- 

 tion of NasHPO4 which was added to the spring water and used 

 in diluting the hay-flour medium. 



Eleven experiments were carried out for ten day periods with 

 protoplasm of different ages and the results are shown in Table V. 



TABLE V. 



EFFECTS OF SODIUM PHOSPHATE ADDED Daily TO THE NORMAL HAY-FLOUR 



MEDIUM. 



In every experiment regardless of the age of the series there was 

 an increase in the division rate. There was however, a marked 

 difference in the amount of increase according to the age of the 

 protoplasm. The youngest series, 129 B in the i6th generation, 

 was stimulated to divide 3.8 divisions more per line than the 

 control series. In the 8oth generation the same series increased 

 its division rate to 4.2 divisions more than the control series. 

 Series 131 B in the 4Oth generation was 5.2 divisions per line 

 ahead of its control series. Series 133 in the QOth generation 

 exceeded the control series by 4.4 divisions per line, in the I44th 

 generation by 7.4 divisions per line, in the ig2d generation by 

 6.6 divisions and in the 2i2th generation by 1.8 divisions per 

 line. Series 131 was stimulated in the lygth generation and 

 showed a division rate of 3.1 divisions ahead of its control series. 



