334 



MOTOR RESPONSES 



the cytoplasm, and the latter, solation. Whether or not this obtains for 

 other salts has not been ascertained. 



Strong alcohol produces' a blister at the point of application, followed 

 by formation of pseudopods on the opposite surface. 



The effect of all these substances is correlated with the kind of chemi- 



Figure 119. The relation between rate of locomotion, gel/sol ratio, and hydrogen-ion 

 concentration in a balanced salt solution. A, Ai, rate of locomotion and gel/sol ratio in 

 solutions containing salts in concentrations given in Table 2 ; B, Bi, rate of locomotion 

 and gel/sol ratio in salts in concentration five times as great as those given in Table 2. 

 Curve A, mean rates of movement of images of amoebae given in Table 2 ; B, means 

 of the rates of movement of seventeen to twenty-four individuals for from five to seven 

 minutes each in each hydrogen-ion concentration; Ai and Bj, mean gel/sol ratios cal- 

 culated from results obtained in measurements made on seventeen to twenty-four indi- 

 viduals in each hydrogen-ion concentration as described above. (After Pitts and Mast, 

 1933.) 



cals, with their concentration in the medium surrounding the amoebae, 

 and with the length of exposure to them. 



If these conclusions are valid, one would expect amoebae in a culture 

 medium to aggregate in regions which are alkaline or which contain 

 relatively little salt. Hopkins (1928) made some observations concern- 

 ing the former. He put specimens into a drop of solution which was 



