60 THE UNIVERSITY OF OKLAHOMA 



in the laboratory and allowed to divide, the resulting cells being iso- 

 lated on depression slides. In this way all of the lines used had a 

 common parentage, representing parts or continuations of the same 

 protoplasm. A control slide was run with each experimental slide, 

 the two being p'aced side by side in the moist chamber in order that 

 any external conditions which might affect one would also affect 

 the other. New experiments were started from the controls, and in 

 the large majority of cases no more than four individuals were 

 present at the time of transference, thus insuring cells of practically 

 the same physiological condition. A 0.2% solution of malted milk, 

 neutralized and sterile, was used as basic medium. Counts of indi- 

 viduals present on control and experimental slides were made daily 

 and the conclusions were based on averages obtained from these 

 results. 



The first experiments were with potassium hydroxide, the 

 range of concentration favorable to acceleration of division being 

 found to lie between 002% and 0.004%. The lower percentage of 

 concentration appeared to produce the more marked increase in 

 rate of growth. The increase produced by the higher concentration 

 though comparatively slight, was constant. A concentration hieher 

 than 00048% caused the death of the cells, indicating that there 

 is a certain range within which potassium hydroxide tends to accel- 

 erate growth, while too great a concentration seems to have an 

 inhibitory effect. 



In considering the effects of ammonium hydroxide attention 

 is called to the fact that this hydroxide is very unstable, and 

 that due to the rapidity with which it evaporates, the investigator 

 cannot always be sure of the concentrations. The results in this 

 experiment are somewhat more irregular than in the preceding 

 one, but the average number of individuals present in each case in- 

 dicates a slight tendency toward acceleration when concentrations 

 of O.C02%, 0.0032% and 0.004% are used. 



The use of sodium hydroxide in the medium also gave inter- 

 esting results. It appears from the data obtained that the addition 

 of this hydroxide in weaker concentrations (0.032% and 0.0032%) 

 shows a decided tendency to accelerate division, while the stronger 

 concentration has an inhibitory effect. 



Barium hydroxide in the concentration of 0.002% and strontium 

 hydroxide in the concentrations of 0.002%, 0.0032%, and 004% 

 were used. In considering the effects, the data at hand would seem 

 to warrant the conclusion that these hydroxides have no effect on 

 the rate of growth. The result from the use of calcium hydroxide 

 in 0.002% and 0.003% solutions are so irregular as to render inter- 



