The Life-History of Hypotrichous Infusoria. 



621 



detrimental/ as was seen to be the case in the work with the two 

 potassium phosphates. As far as these experiments go they would 

 seem to indicate that potassium has more effect than sodium on 

 the metabolic activity of Gastrostyla. 



5. Experiments with Potassium Sulphate and Magnesium 



Sulphate. 



The third series of experiments was with y"^ and 3^ solutions 

 of K2SO4 and MgS04. The results of the eight cultures together 



Potassium Bromid. 

 KBr 



Diagram XII. 



Effect of initial and daily stimulation with KBr, ^ and ^^, on the division-rate of Gastrostyla. 

 Averages are for five-day periods. The four experiments plotted in this diagram were carried on simul- 

 taneously from August 30, to September 19, 1904. Method of plotting is the same as in Diagram Vm. 



with the control are shown in Diagram XI, and they indicate that 

 an initial application of K2SO4 in both dilutions used produced a 

 slight acceleration in the division-rate, whereas MgS04 under the 

 same conditions produced a retardation. It is evident here again 

 that the daily use of the salts was invariably detrimental; and also 



'The omission of the curve at certain points is due to accidental loss of the specimens under experi- 

 mentation. 



