346 H. S. JENNINGS 



For changing the animals to this, two fresh sHdes are prepared, 

 each containing three drops of this fresh fluid. A vessel of boil- 

 ing water is at hand; also a supplementary vessel of the fresh 

 culture fluid. The capillary pipette is first dipped in boiling 

 water, then into the fresh culture fluid, then a single individual 

 is removed with it from the old slide to the first new slide. The 

 pipette is then again disinfected in boiling water and washed in 

 the supplementary dish of culture fluid. Meanwhile, the removed 

 Paramecium has been swimming about violently in the three 

 drops of fresh culture fluid, thus washing itself largely free from 

 the bacteria introduced with it. Now, with the cleaned pipette, 

 it is retransferred from this wash water to the second slide of 

 fresh fluid. (In much of my work I gave each animal a second 

 washing in the same way.) 



A new 'wash slide' is then prepared, the pipette is disinfected 

 and washed as before, and we proceed to transfer in the same 

 way an individual from the second slide to the wash water and 

 then to its definitive slide. After every transfer the pipette must 

 be disinfected and washed, and new wash water must be used for 

 every individual transferred. 



Experience shows that all the details of this painful process 

 are quite necessary if the conditions are to be kept uniform in a 

 large number of lines. Carrying this out for some 250 lines for 

 nearly a month I found so exhausting as to make it practically 

 impossible to continue the experiment for a longer period. 



Records. The records of the conjugant and non-conjugant 

 lines for this experiment, conducted in the manner just described, 

 are given in tables 34 and 35 (Appendix). The results of this 

 experiment are of so fundamental an importance for the subject 

 with which the present series of papers deals that I feel it neces- 

 sary to give the records in detail, showing the number of fissions 

 that occurred in each period of two days. These records will be 

 used farther in studies on inheritance, to follow the present 

 paper. 



Explanation, of tables 34 and 35. These tables give, for the conju- 

 gants and non-conjugants, respectively, of the pure strain E, the records 

 of fissions for each line for the entire period (twenty-four days for the 



